EPA/ROD/R04-99/0701999

  EPA Superfund

   

Record of Decision:

   

HOMESTEAD AIR FORCE BASEEPA ID:  FL7570024037OU 07HOMESTEAD AIR FORCE BASE, FL09/29/1999

Homestead Air Reserve Base, Florida

Final

Record of Decision forOperable Unit No. 7.Entomology Storage Area

January 1998

DEPARTMENT OF THE AIR FORCEAIR FORCE RESERVE

MEMORANDUM FOR: SEE DISTRIBUTION January 29,1998

FROM: 482d SPTG/CEV29050 Coral Sea Blvd.Bldg. 232Homestead ARS, F1 33039-1299

SUBJECT: Final Operable Unit 7 Record Of Decision

Attached is the Final Record Of Decision for OU-7. Asnoted in the Responsiveness Summary Section of the Report,there were no comments received during the comment period orpublic meeting. If you have any questions please contact me at(305) 224-7163.

Attachment:Final Operable Unit 7 Record Of Decision

cc:482d SPTG/CEV, Mr. John B. Mitchell (2)AFBCA/DD Homestead, Mr. Tom Bartol (2)HQ AFRC/CEVV, Ms. Valerie Stacey (1)USACE CENWO-ED-EE , Ms. Taunya Howe (4)Gannett Fleming, Hugh Vick (1)

DISTRIBUTION: U.S. EPA, Doyle T. BrittainFDEP, Jorge R. CasparyDERM, James A. Carter

March 5, 1998

Colonel Richard J. EustaceCommanderHomestead Air Force Base360 Coral Sea BoulevardHomestead, Florida 33039-1299

Dear Colonel Eustace:

The Florida Department of Environmental Protectionagrees with the Air Force’s selected alternative foroperable Unit 7 (Site SS-7), Entomology Storage Area atHomestead Air Reserve Base.

The Record of Decision specifies Capping, Access andUse Restrictions for Soil and Groundwater, NaturalAttenuation and Groundwater Monitoring at Site SS-7 as acost effective remedy that provides adequate protection ofpublic health, welfare, and the environment. Thedetermination to implement the above course of action atthis site is consistent with the ComprehensiveEnvironmental Response, Compensation, and Liability Act(CERCLA) as amended by the Superfund Amendments andReauthorization Act (SARA) and the National ContingencyPlan (40 CFR 300). Accordingly, the site shall undergo afive-year review with the costs of the review to beabsorbed by the federal government.

We appreciate your continued cooperation and lookforward to an expeditious economic and environmentalrecovery of Homestead Air Reserve Base.

VBW/jrc

Department of

Environmental ProtectionTwin Towers Office Building

2600 Blair Stone RoadTallahassee, Florida 32399-2400

March 19, 1998

Mr. John B. MitchellAFRES 482nd Reserve Wing360 Coral Sea BlvdHomestead ARB, FL 33039-1299

RE: Record Of Decision for Operable Unit 7.Homestead ARB, Florida

Dear Mr. Mitchell:

The Department concurs with the selected alternativedetailed in the above referenced document dated January1998 (received January 30, 1998). I am enclosing aconcurrence letter signed by Secretary Virginia Wetherell.You are encouraged to proceed with groundwater monitoringat OU-7 at your earliest convenience.

If I can be of any assistance in this matter, pleasecontact me at 904/488-3935.

09/23/1999 15:35 3052247381 482SPTG/BCE PAGE 01

Phone: 305-224-7344Fax: 305-224-7347

FaxTo: Doyle Brittain From: 482 sptg/ce

Fax: 404-562-8518 Date: September 23, 1999

Phone: 404-562-8549 Pages: 3

Re: OU-7 cc:

9 Urgent 9 For Review 9 Please Comment 9 Please Reply 9 Please Recycle

HOMESTEAD ARB,482

09/23/1999 15:35 3052247381 482SPTG/BCE PAGE 02

DEPARTMENT OF THE AIR FORCEAIR FORCE RESERVE

MEMORANDUM FOR SEE DISTRIBUTION September 23,1999

FROM: 482d SPTG/CEV29050 Coral Sea Blvd.Bldg, 232Homestead ARS, Fl 33039-1299

SUBJECT: Insertion of Institutional Control language into the Record of Decision forOU-7 Entomology Storage Area

Enclosed please find a copy of a paragraph to be inserted into the Record of Decision datedJanuary, 1998 for OU-7. This paragraph incorporates language committing to institutionalcontrols as included in the Land Use Control Implementation Plan (LUCIP) for this site.

If you have any questions, please do not hesitate to contact me at (305) 224-7163.

Attachment:ROD Insertion

Cc:HQ AFRC/CEVV, Mr. Philippe MontaigneAFBCE/DD Homestead, Mr. Tom BartolGannett Fleming, Hugh Vick

DISTRIBUTION:U.S. EPA. Doyle T. BrittainFDEP. Jorge R. CasparyDERM, James A. Carter

09/23/1999 15:35 3052247381 482SPTG/BCE PAGE 03

RECORD OF DECISIONOPERABLE UNIT SEVEN

MOA INCORPORATION LANGUAGE

By separate Memorandum of Agreement (MOA) dated 15 March, 1999, with U.S.Environmental Protection Agency (U.S. EPA) and the Florida Department ofEnvironmental Protection (FDEP), HARS, on behalf of the Department of the AirForce, agreed to implement base-wide, certain periodic site inspection, conditioncertification and agency notification procedures designed to ensure the maintenanceby Installation personnel of any site-specific Land Use Controls (LUCs) deemednecessary for future protection of human health and the environment. A fundamentalpremise underlying execution of that agreement was that through the Air Force’ssubstantial good-faith compliance with the procedures called for therein, reasonableassurances would be provided to U.S. EPA and FDEP as to the permanency of thoseremedies which included the use of specific LUCs.

Although the terms and conditions of the MOA are not specifically incorporated ormade enforceable herein by reference, it is understood and agreed by the Air Force,U.S. EPA and FDEP that the contemplated permanence of the remedy reflectedherein shall be dependent upon the Installation’s substantial good-faith compliancewith the specific LUC maintenance commitments reflected therein, Should suchcompliance not occur or should the MOA be terminated it is understood that theprotectiveness of the remedy concurred in may be reconsidered and that additionalmeasures may need to be taken to adequately ensure necessary future protection ofhuman health and the environment.

Land Use Controls Implemented:

Homestead ARS Installation Restoration Manager coordinates inspections andforwards discrepancies for correction.

Restrict construction. Workers must be notified that contamination exists and OSHAregulations apply if excavation activities are proposed on the site. Obtain concurrencefrom USEPA and FDEP prior to design. No residential usage allowed. Restrictgroundwater and soil access. No water supply wells allowed within the restricted areaPrior to all construction activities, a dig permit is required which also restrictsgroundwater and soil access for this site.

Objective:

Prevent direct contact with contaminated media. Prevent trespassers and residentialuse.

UNITED STATES ENVIRONMENTAL PROTECTION AGENCYREGION 4

ATLANTA FEDERAL CENTER61 FORSYTH STREET

ATLANTA, GEORGIA 30303-8960

CERTIFIED MAILRETURN RECEIPT REQUESTED

4WD-FFB

Maj Gen. David. R. SmithVice Commander, AFRC/CV155 Second StreetRobins AFB, GA 31098-1635

SUBJ: Record Of Decision - Operable Unit 7Homestead Air Force Base NPL SiteHomestead, Florida

Dear Maj Gen Smith

The U.S. Environmental Protection Agency (EPA) Region IV has reviewed the subjectdecision document and concurs with the selected remedy for the remedial action at Operable Unit(OU) 7 at the former Homestead Air Force Base (HAFB). This remedy is supported by thepreviously completed Remedial Investigation, Feasibility Study, and Baseline Risk AssessmentReports. The selected remedy consists Land Use Controls which include: • Capping of the site through new construction,• Controls to prevent residential development and placement of a potable well,• Digging excavation restrictions around areas with elevated arsenic,• Install one new groundwater monitoring well,• Groundwater monitoring for organochlorine pesticides, BNAs, and TAL metals, and• One five-year review.

The determination to implement this course of action at this site is consistent with theComprehensive Environmental Response, Compensation, and Liability Act (CERCLA) asamended by the Superfund Amendments and Reauthorization Act (SARA) and the NationalContingency Plan (40 CFR 300).

Concurrence with the Record of Decision (ROD) is conditioned on the expressunderstanding that the Air Force is committed to the agreement reached with IV and the FloridaDepartment of EPA Region. Environmental Protection (FDEP) that complies with EPA’s April21, 1998 Memorandum titled “Assuring Land Use Controls at Federal Facilities.” We reiterate, aswe advised Air Force Regional Environmental Office representatives in our meeting on May 21,1998, our concurrence with this particular ROD is based on the

2

understanding that the Air Force is committed to the Memorandum of Agreement (MOA)consistent with the above-referenced Land Use Control (LUC) Policy. Furthermore, theHomestead Air Force Base BRAC Cleanup Team (BCT) will be expected to craft specificprovisions for Land Use Controls as part of the resulting Land Use Control Implementation Planfor OU- 7. that will prohibit residential land use.

EPA appreciates the level of effort that was put forth in the documents leading to thisdecision, EPA looks forward to working with HAFB as we move towards final cleanup of theNational Priorities List (NPL) site.

If you have any questions, please call me at (404) 562-8651, or Doyle T. Brittain at (404)562-8549.

cc: Thomas J. Bartol, HAFB/AFBCA John Mitchell, HAFB/AFRES Jim Woolford, EPA/FFRO Jorge Caspary, FDEP

FINAL

RECORD OF DECISION

FOR

OPERABLE UNIT 7ENTOMOLOGY STORAGE AREA

Homestead Air Reserve Base, Florida

January 1998

Prepared for:

U. S. Army Corps of EngineersMissouri River Division

Omaha DistrictOmaha, Nebraska

Prepared by:

Montgomery Watson3501 N. Causeway Blvd.Metairie, Louisiana 70002

RECORD OF DECISION

Operable Unit 7Entomology Storage Area

Homestead Air Reserve BaseHomestead, Florida

FDEP Facility No. 138521996

January 1998

Montgomery Watson appreciates the opportunity to work for the U.S. Army Corps of Engineers, atthe Homestead Air Reserve Base facility in Homestead, Florida. If you have any questions orcomments concerning this report, please contact Mr. John B. Mitchell, Remedial Program Manager,Homestead Air Reserve Base.

Respectfully submitted,

MONTGOMERY WATSON

Homestead Air Reserve Base, FloridaOperable Unit 7,Entomology Storage Area

Declaration for the Record of Decision

1

DECLARATION STATEMENT

FOR THE

RECORD OF DECISION FOR OPERABLE UNIT NO. 7

SITE NAME AND LOCATION

Homestead Air Reserve BaseHomestead, Dade County, FloridaOperable Unit No. 7, Site SS-7,Entomology Storage Area (Former Site P-2)

STATEMENT OF BASIS AND PURPOSE

This decision document presents the selected remedial action for the former Entomology StorageArea, Operable Unit No. 7 (OU-7), at Homestead Air Reserve Base (ARB) (formerly Homestead AirForce Base), in Homestead, Florida. The selected remedial action is chosen in accordance withCERCLA, as amended by SARA, and, to the extent practicable, the National Oil and HazardousSubstances Pollution Contingency Plan (NCP). This decision document explains the basis forselecting the remedial alternative for this Operable Unit. The information that forms the basis for thisremedial action is contained in the administrative record for OU-7.

The selected alternative for OU-7 is capping by recent construction, access and use restrictions forsoil and groundwater, and groundwater monitoring to detect any potential migration of groundwatercontaminants. The State of Florida, the U.S. Environmental Protection Agency (USEPA), and theU.S. Air Force (USAF) concur with the selected remedy presented in this Record of Decision (ROD).

ASSESSMENT OF THE SITE

Actual or threatened releases of hazardous substances from this site, if not addressed by implementingthe response action selected in this ROD, may present an imminent and substantial endangerment topublic health, welfare, or the environment.

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DESCRIPTION OF THE SELECTED REMEDY

The operable unit represents the only unit for the site. This response action reduces the principlethreat at the site by including the recent construction of the new Civil Engineering and POL Complexas available cover/cap to prevent exposure to site soils. It also requires the implementation of accessand use restrictions for soil and groundwater, and groundwater monitoring.

The major components of the selected remedy include:

• Capping of the site by recent construction of buildings, pavement, and grassways toprevent exposure to soil and groundwater contaminants.

• Land use restrictions to prevent digging/excavation activities around areas whereelevated concentrations of arsenic were detected in soil and groundwater.

• Institutional controls to prevent the placement of potable water wells into thegroundwater beneath the site.

• Installation of one shallow groundwater well and groundwater monitoring for 5 yearsif necessary. The groundwater samples will be analyzed for organochlorine pesticides,BNAs, and TAL metals.

• Five year review to determine whether the remedy remains protective of human healthand the environment.

STATUTORY DETERMINATIONS

The selected remedy is protective of human health and the environment and through the use of agroundwater ARARs waiver, complies with federal and state requirements that are legally applicableor relevant and appropriate to the remedial actions. Because this site is in that portion of the base tobe retained by the Air Force Reserves, the industrial scenario has been deemed appropriate forevaluating site risk. Risk levels at the site are below the EPA remediation-based risk benchmarks forboth current and future base workers, but slightly exceed the state of Florida’s target cancer risk ofIE-06.

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Under current and future industrial land use conditions, this alternative is protective of human healthand the environment by using capping by recent construction and institutional controls to preventexposure to soils and groundwater. With this alternative, site risk do not present a threat to humanhealth or the environment, therefore, the more cost effective remedial action is being implementedbased on evaluation of this risk and potential site usage.

Because this remedy will result in hazardous substances remaining on-site above health-based levels(arsenic in groundwater), a review will be conducted within five years after commencement ofremedial action to ensure that the remedy continues to provide adequate protection of human healthand the environment. The review will be performed every five years thereafter until protectivenessis achieved.

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Record of DecisionOperable Unit No. 7

United States Air Force Reserve Command Robins Air Force Base, Georgia

Homestead Air Reserve Base, FloridaOperable Unit 7,Entomology Storage Area

Decision Summary for theRecord of Decision

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TABLE OF CONTENTS

Page

SECTION 1.0 - SITE NAME, LOCATION, AND HISTORICAL DESCRIPTION . . . . . . . . . 1

1.1 Site Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.2 Regional Land Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31.3 Surface Hydrology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.3.1 Regional Hydrogeologic Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41.4 Site Geology and Hydrogeology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

SECTION 2.0 - SITE HISTORY AND ENFORCEMENT ACTIVITIES . . . . . . . . . . . . . . . . . 6

2.1 Operable Unit No. 7 History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62.1.1 Past Site Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62.1.2 Current Site Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

2.2. Enforcement History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62.2.1 CERCLA Regulatory History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

2.3 Investigation History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92.3.1 IRP Phase I - Record Search . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92.3.2 IRP Phase II - Confirmation/Qualification . . . . . . . . . . . . . . . . . . . . . . . 102.3.3 IRP Phase III - Technology Base Development . . . . . . . . . . . . . . . . . . . 102.3.4 IRP Phase IV - Additional Investigations . . . . . . . . . . . . . . . . . . . . . . . 10

2.3.4.1 IRP Phase IV-A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102.3.4.2 1988 Investigations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112.3.4.3 1989 Investigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

2.3.5 1991 Remedial Investigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122.3.6 1993 Remedial Investigation Addendum . . . . . . . . . . . . . . . . . . . . . . . . 132.3.7 1994 Investigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

2.4 Community Relations History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162.5 Scope and Role of Response Action . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172.6 Summary of Site Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

2.6.1 Nature and Extent of Contamination . . . . . . . . . . . . . . . . . . . . . . . . . . . 182.6.1.1 Summary of Soil/Bedrock Investigations . . . . . . . . . . . . . . . . . 192.6.1.2 Nature and Extent of Soil/Bedrock Contamination . . . . . . . . . . 222.6.1.3 Summary of Groundwater Investigations . . . . . . . . . . . . . . . . . 252.6.1.4 Nature and Extent of Groundwater Contamination . . . . . . . . . . 262.6.1.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

ii

TABLE OF CONTENTS(continued)

Page

2.6.2 Potential Routes of Migration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 342.7 Summary Of Site Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

2.7.1 Selection of Chemicals of Potential Concern . . . . . . . . . . . . . . . . . . . . . . . . . . . 362.7.1.1 Criteria for Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 362.7.1.2 Concentration-Toxicity Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 372.7.1.3 Data Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 382.7.1.4 Screening Using Risk-Based Concentrations . . . . . . . . . . . . . . . . . . . . 402.7.1.5 Chemicals of Potential Concern Selection Process . . . . . . . . . . . . . . . . 41

2.7.2 Potential Routes of Migration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 432.7.3 Exposure Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 452.7.4 Toxicity Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 492.7.5 Risk Characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

2.7.5.1 Carcinogenic Risks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 522.7.5.2 Chronic Health Risks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 532.7.5.3 Risks Associated with Exposure to Groundwater . . . . . . . . . . . . . . . . . 542.7.5.4 Risks Associated with Exposure to Soils . . . . . . . . . . . . . . . . . . . . . . . 552.7.5.5 Lead . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 572.7.5.6 Total Site Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 582.7.5.7 Development of Remedial Goal Options . . . . . . . . . . . . . . . . . . . . . . . . 62

2.7.6 Ecological Risk Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 632.8 Description of Alternatives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

2.8.1 Alternative 1 - No Action . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 652.8.2 Alternative 2 - Access and Use Restrictions for Soil and Groundwater

and Groundwater Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 652.9 Summary of Comparative Analysis of Alternatives . . . . . . . . . . . . . . . . . . . . . . 67

2.9.1 Overall Protection of Human Health and Environment . . . . . . . . . . . . . . . . . . . 672.9.2 Compliance with ARARs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 682.9.3 Long-term Effectiveness and Permanence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 682.9.4 Reduction of Mobility, Toxicity, or Volume through Treatment . . . . . . . . . . . . 682.9.5 Short-term Effectiveness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 682.9.6 Implementability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 682.9.7 Cost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 692.9.8 State and Community Acceptance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

2.10 Selected Remedy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 692.11 Statutory Determinations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 692.12 Documentation of Significant Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

iii

LIST OF FIGURESFigure Follows

No. Title Page

1-1 Location of Homestead Air Force Base . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1-2 Future Land Use Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1-3 Base Location Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1-4 Former Site Location Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1-5 Current Site Location Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2-1 Site Locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2-2 Phase II Sampling Locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102-3 Phase IV 1988 Sampling Locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112-4 Phase IV 1989 Sampling Locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112-5 1991 and 1993 Sampling Locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122-6 Delineation Sampling Grid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142-7 Confirmation Sampling Points, North Excavation . . . . . . . . . . . . . . . . . . . . . . . . . . . 142-8 Confirmation Sampling Points, South Excavation . . . . . . . . . . . . . . . . . . . . . . . . . . . 142-9 Final Excavation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142-10 Groundwater Sampling Locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252-11 Arsenic/Pesticide Concentrations in Groundwater 1991 and 1993 Data . . . . . . . . . . . 34

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LIST OF TABLESFigure Follows

No. Title Page

2-1 Pesticides Stored at Homestead Air Reserve Base, Florida . . . . . . . . . . . . . . . . . . . . 6 2-2 Analytical Results of Groundwater Samples Collected during

Phase II Investigations at OU-7, Entomology Storage Area . . . . . . . . . . . . . . . . . . . . 102-3 Analytical Results of Phase IV Soil Samples Collected in 1988 at

OU-7, Entomology Storage Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112-4 Analytical Results of Phase IV Groundwater Samples Collected in 1988 at

OU-7, Entomology Storage Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112-5 Results of Field Analyses of Phase IV Groundwater Samples Collected in

1988 and 1989 at OU-7, Entomology Storage Area . . . . . . . . . . . . . . . . . . . . . . . . . . 112-6 Results of Organic Vapor Analyses of Phase IV Soil Samples Collected in

1989 at OU-7, Entomology Storage Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112-7 Analytical Results of Phase IV Soil Samples Collected in 1989

at OU-7, Entomology Storage Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112-8 Summary of Analytical Results for Phase IV Groundwater Samples

Collected in 1989 at OU-7, Entomology Storage Area . . . . . . . . . . . . . . . . . . . . . . . 122-9 Confirmation Sampling Parameters, OU-7, Entomology

Storage Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142-10 Summary of Soil Samples from Excavated Areas, OU-7,

Entomology Storage Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152-11 Summary of Corrective Action Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212-12 Background Soil Concentrations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212-13 Post Excavation Summary of Constituents Detected in Soil/Bedrock . . . . . . . . . . . . . 222-14 Concentrations of Dissolved Inorganic Constituents in the Biscayne Aquifer

in Dade County, Florida . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262-15 Groundwater Quality Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262-16 Summary of 1991 Groundwater Analytical Results . . . . . . . . . . . . . . . . . . . . . . . . . . 262-17 Summary of 1993 Groundwater Analytical Results . . . . . . . . . . . . . . . . . . . . . . . . . . 272-18 Summary of Chemicals of Potential Concern in Groundwater . . . . . . . . . . . . . . . . . . 372-19 Summary of Chemicals of Potential Concern in Surface Soil . . . . . . . . . . . . . . . . . . . 372-20 Summary of Chemicals of Potential Concern in Subsurface Soil . . . . . . . . . . . . . . . . . 372-21 Toxicity-Concentration Screening for Chemicals in Groundwater at

OU-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 382-22 Toxicity-Concentration Screening for Chemicals in Surface Soil at

OU-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 382-23 Toxicity-Concentration Screening for Chemicals in Subsurface Soil at

OU-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 382-24 RBC-Based Benchmark Screening for Chemicals in Groundwater at

OU-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 402-25 RBC-Based Benchmark Screening for Chemicals in Surface Soil at

OU-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 402-26 RBC-Based Benchmark Screening for Chemicals in Subsurface Soil at

OU-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

LIST OF TABLES

Figure Follows No. Title Page

2-27 Chemicals of Potential Concern in Environmental Media at OU-7 . . . . . . . . . . . . . . . 422-28 Exposure Point Concentrations for Groundwater . . . . . . . . . . . . . . . . . . . . . . . . . . . . 462-29 Exposure Point Concentrations for Surface Soil Samples . . . . . . . . . . . . . . . . . . . . . . 462-30 Exposure Point Concentrations for Subsurface Soil Samples . . . . . . . . . . . . . . . . . . . 462-31 Example Data Reduction Calculation for Arsenic in Groundwater Samples

at OU-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 472-32 Potential Pathways of Exposure to Chemicals Detected at OU-7 . . . . . . . . . . . . . . . . 472-33 Dermal and Oral Absorption Efficiencies for Chemicals of Potential

Concern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 502-34 Reference Doses for Chemicals of Potential Concern at OU-7 . . . . . . . . . . . . . . . . . . 502-35 Cancer Slope Factors, Tumor Sites, and USEPA Cancer Classifications for

Chemicals of Potential Concern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 512-36 Adjusted Toxicity Values Used to Assess Dermal Exposure at

OU-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 512-37 Groundwater Ingestion Exposure Doses and Risk Calculations for a

Hypothetical Future Adult Resident at OU-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 542-38 Soil Exposure Doses and Risk Calculations for a Potential Current Base

Worker at OU-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 552-39 Soil Exposure Doses and Risk Calculations for Hypothetical Future

Adult Resident at OU-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56240 Soil Exposure Doses and Risk Calculations for Hypothetical Future

Child Resident at OU-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56241 Soil Exposure Doses and Risk Calculations for Hypothetical Future

Construction Worker at OU-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 562-42 Modeled Blood Lead Levels in Hypothetical Children (Aged 0 to 6) . . . . . . . . . . . . . 572-43 Summary Table of Hazard Indices and Cancer Risks for all Scenarios . . . . . . . . . . . . 582-44 Risk-Based Remedial Goal Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 632-45 Comparative Analysis of Remedial Alternatives, OU-7 . . . . . . . . . . . . . . . . . . . . . . . 67

v

1

DECISION SUMMARY

FOR THE

RECORD OF DECISION

1.0 SITE NAME, LOCATION, AND HISTORICAL DESCRIPTION

Homestead Air Reserve Base (ARB) is located approximately 25 miles southwest of Miami and 7miles east of Homestead in Dade County, Florida (Figure 1-1). The main Installation coversapproximately 2,916 acres while the surrounding areas are semi-rural. The majority of the Base issurrounded by agricultural land. The land surface at Homestead ARB is relatively flat, with elevationsranging from approximately 5 to 10 feet above mean sea level (msl). The Base is surrounded by acanal (Boundary Canal) that discharges to Outfall Canal and ultimately into Biscayne Bayapproximately 2 miles east.

The Biscayne Aquifer underlies the Base and is the sole source aquifer for potable water in DadeCounty. Within 3 miles of Homestead ARB over 4,000 area residents obtain drinking water from theBiscayne Aquifer while 18,000 acres of farmland are irrigated from aquifer wells (USEPA, 1990).All recharge to the aquifer is through rainfall.

Homestead Army Air Field, a predecessor of Homestead Air Reserve Base, was activated inSeptember 1942, when the Caribbean Wing Headquarters took over the air field previously used byPan American Air Ferries, Inc. The airline had developed the site a few years earlier for pilot training.Prior to that time, the site was undeveloped. Initially operated as a staging facility, the field missionwas changed in 1943 to training transport pilots and crews.

In September 1945, a severe hurricane caused extensive damage to the air field. The Base propertywas then turned over to Dade County and was managed by the Dade County Port Authority for thenext eight years. During this period, the runways were used by crop dusters and the buildings houseda few small industrial and commercial operations.

In 1953, the federal government again acquired the airfield, together with some surrounding property,and rebuilt the Site as a Strategic Air Command (SAC) Base. The Base operated under SAC untilJuly 1968 when it was changed to the Tactical Air Command (TAC) and the

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4531st Tactical Fighterwing became the new host. The Base was transferred to Headquarters AirCombat Command (HQ/ACC) on June 1, 1992.

In August 1992, Hurricane Andrew struck south Florida causing extensive damage to the Base. TheBase was placed on the 1993 Base Realignment and Closure (BRAC) list and slated for realignmentwith a reduced mission. Air Combat Command departed the Base on March 31, 1994 with Air ForceReservists activated at the Base on April 1, 1994. The 482nd Reserve Fighter Wing now occupiesapproximately 1/3 of the Base with the remaining 2/3 slated for use and oversight by Dade County.Figure 1-2 depicts the proposed future land use for the Base.

1.1 SITE DESCRIPTION

The Homestead ARB location is depicted in Figure 1-3. Operable Unit 7 originally encompassed atriangular area of approximately 5,265 square feet or approximately 0.13 acres and is located in thewest-central portion of Homestead ARB. The Entomology Storage Area was a fenced triangular arealocated in the southeast corner of the Civil Engineering Storage Compound, which was a storage areafor supplies and equipment. The OU-7 investigation area was later expanded to approximately 4 acreswhich included a large portion of the Civil Engineering Storage Compound, OU-3 PCB Spill Area,the asphalt pavement areas, and a portion of the Building 207, Site ST-18 petroleum contaminatedsite. The majority of the site features/structures were razed due to the Interim Removal Actionperformed in 1994, and rebuilding activities by the Air Force Reserves. A site map depicting theformer surface features is provided as Figure 1-4.

The OU-7 study area was bordered by a concrete wall at the western edge of the Civil EngineeringStorage Compound; roofed concrete car racks to the east; an asphalt parking area and Building 220to the north; and open land consisting of crushed and weathered limestone covered by grass to thesouth. The limestone bedrock, which was exposed at the surface over much of the area, is generallycharacterized as highly weathered and is penetrable with a split-spoon formation sampler. A January13, 1983, aerial photograph indicates railroad tracks formerly existed between the fence and theroofed concrete car racks.

A drainage canal borders the former Civil Engineering Storage Compound to the west. This drainagecanal typically contains water to a depth of to 2 feet. The drainage canal flows from southeast tonorthwest and then to the west before draining into the Boundary Canal,

3

which borders Homestead ARB. The concrete wall on the eastern side of the drainage canal divertssurface water run-off from OU-7 away from the canal. The date of construction of the concrete wallis not available.

Operable Unit 7 has been retained by the 482nd Air Force Reserves as part of the Cantonment Area.Expansion of this area by the Air Force Reserves included rebuilding over the site for a new BaseSupply, Civil Engineering, and POL Operations Area. The former OU-7 area is now occupied by anew civil engineering complex, three shops, a storage area, miscellaneous buildings, expanded parkingareas, and grassways. Figure 1-5 depicts the current layout of the OU-7 study area.

1.2 REGIONAL LAND USE

The area adjacent to Homestead ARB, including OU-7, to the west, east, and south within a half-mileradius is primarily composed of farmland and plant nurseries. Residential areas are located within ahalf-mile to the north and southwest of the Base. Woodlands are located approximately one-half-mileeast of the facility and mangroves and marsh occur adjacent to Biscayne Bay. The Biscayne NationalPark is located 2 miles east of Homestead ARB; the Everglades National park is located 8 mileswest-southwest of the Base; and the Atlantic Ocean is approximately 8 miles east of the Base.

1.3 SURFACE HYDROLOGY

Surface hydrology at Homestead ARB, including OU-7 is controlled by five main factors: 1) relativelyimpermeable areas covered by runways, buildings and roads; 2) generally high infiltration ratesthrough the relatively thin layer of soil cover; 3) flat topography; 4) generally high infiltration ratesthrough the outcrop locations of the Miami Oölite Formation; and 5) relatively high precipitation ratecompared to evapotranspiration rate. Infiltration is considered to be rapid through surfaces of oöliteoutcrop and areas with a thin soil layer. Infiltration rates are accelerated by fractures within the oölite,as well as naturally occurring solution channels. Precipitation percolates through the relatively thinvadose zone to locally recharge the unconfined aquifer.

Natural drainage is limited because the water table occurs at or near land surface. The constructionof numerous drainage canals on Homestead ARB has improved surface water drainage and loweredthe water table in some areas. Rainfall runoff from within Homestead ARB boundaries is drained viadiversion canals to the Boundary Canal.

4

A drainage divide occurs within the Homestead ARB facility property, running from the northern endof the facility, toward the center. Water in the Boundary Canal flows generally south and east alongthe western boundary of the property, and south along the eastern boundary, converging at astorm-water reservoir located at the southeastern corner of the Base. Flow out of the stormwaterreservoir flows into Outfall Canal, which, in turn, flows east into Biscayne Bay, approximately 2 mileseast of the Base. Water movement is typically not visible in the canals in dry weather due to thelowered water table and the very low surface gradient (0.3 feet per mile) that exists at the Base.

1.3.1 Regional Hydrogeologic Setting

The regional hydrogeology in the southeast Florida area consists of two distinct aquifers: the surficialaquifer system, which consists of the Biscayne Aquifer and the Grey Limestone Aquifer, and thelower aquifer, the Floridan Aquifer.

Biscayne Aquifer. The Biscayne Aquifer at Homestead ARB consists of the Miami Oölite, FortThompson Formation, and the uppermost part of the Tamiami Formation. In general, the mostpermeable parts of the aquifer lie within the Miami Oölite and the Fort Thompson Formation.

The Biscayne Aquifer underlies all of Dade, Broward, and southeastern Palm Beach Counties. TheBiscayne Aquifer is the sole source of potable water in Dade County and is a federally-designatedsole-source aquifer pursuant to Section 1425 of the Safe Drinking Water Act (SDWA). The BiscayneAquifer supplies drinking water to approximately 2.5 million people within local communities. Allrecharge to the aquifer is derived from local rainfall, part of which is lost to evaporation,transpiration, and runoff.

The Biscayne Aquifer has reported transmissivities ranging from approximately 4 to 8 million gallonsper day per foot (mgd/ft) (Allman et al., 1979).

Water-table contours indicate that under natural conditions, groundwater flows southeasterly towardBiscayne Bay. The hydraulic gradient is approximately 0.3 ft/mile. The water table at HomesteadARB generally is encountered within 5 to 6 feet of land surface, but may occur at or near land surfaceduring the wet season (May to October). Fluctuations of groundwater levels and local variations inthe direction of groundwater flow are due to several factors: (1) differences in infiltration potential,(2) runoff from paved areas, (3) water-level

5

drawdown near pumping wells, (4) significant but localized differences in lithology (e.g., silt-filledcavities) and (5) drainage effects of canals and water-level control structures.

Floridan Aquifer. Underlying the low-permeability sediments of the Tamiami Formation andHawthorn Group are the formations which constitute the Floridan Aquifer.

The Floridan Aquifer is made up of limestones and dolomites. It is under artesian pressure and waterlevels in deep wells may rise 30 to 40 ft above ground surface. Groundwater within these Mioceneand Eocene age formations tends to contain dissolved constituents at levels significantly above thoserecommended for drinking water. In view of the poor water quality and the depth of water yieldingzones (800 to 900 feet below ground surface (bgs)), the Floridan Aquifer is of limited usefulness asa source of potable water supply in the study area.

1.4 SITE GEOLOGY AND HYDROGEOLOGY

The stratigraphy of the shallow aquifer system as determined from soil borings performed during siteinvestigations by Geraghty & Miller (G&M) and Montgomery Watson consists of a surficialweathered Miami Oölite ranging in depth from 2 to 6 feet bgs. The weathered limestone consists ofa white to brown semi-consolidated oölitic limestone. This strata is underlain by consolidated tosemi-consolidated oölitic and coral limestone interbedded with coarse to fine sand and clayey sandlayers and lenses down to the total depth of borings (approximately 40 feet bgs).

The Biscayne Aquifer is one of the most transmissive aquifers in the world. It underlies HomesteadARB. A thin vadose zone, nominally less than 5 feet deep, overlays the groundwater table at the site.As previously stated, the aquifer structure is a calcium carbonate matrix. This lithology is known tohave natural concentrations of target analyte list (TAL) metals. In descending order by concentration,calcium, aluminum, iron magnesium, sodium, and potassium can be considered the primary metalsof carbonate rock. The other TAL metals occur in trace concentrations, less than 50 milligrams perkilogram (mg/kg). It should be expected that, as precipitation infiltrates and recharge takes place,leaching of metal ions from the weathered vadose zone and shallow unsaturated zone occurs.Regional data collected suggest that concentrations of trace metals can be expected to be the greatestin the shallow portion of the aquifer because of the proximity to the source (i.e., the weatheringvadose structure). These observations support a hydrogeologic model in which the shallow portionof the aquifer has a greater horizontal transmissivity than the vertical

6

component during recharge events. The conceptual model that the shallow groundwater isdischarging to the ditches and canals provides sufficient detail for the purpose of discussing OU-7.

2.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES

2.1 OPERABLE UNIT NO. 7 HISTORY

2.1.1 Past Site Usage

The former Entomology Storage Area was used in the 1960s as a storage area for bulk quantities ofpesticide compounds. Diesel fuel was also reportedly stored in the southern portion of the site.Operable Unit 7 was later expanded to include a large portion of the Civil Engineering StorageCompound, a former petroleum contaminated site, Building 207 (Former Site ST-18) and OU-3(Former PCB Spill Area), increasing the total area to approximately 4 acres. A list of pesticidesstored on Homestead ARB are presented in Table 2-1. The dates and quantities of pesticides anddiesel fuel stored at the site are not available.

2.1.2 Current Site Usage

The OU-7 area has been retained by the 482nd Air Force Reserve as part of the cantonment area. Thesite was rebuilt by the Air Force Reserves in 1996 as part of the new Base Supply, Civil Engineering,and POL Operations area. Operable Unit 7 is now occupied by a new civil engineering complex, threeshops, a storage area, miscellaneous buildings and a expanded parking areas, and grassways.

2.2. ENFORCEMENT HISTORY

2.2.1 CERCLA Regulatory History

The Comprehensive Environmental Response, Compensation and Liability Act of 1980 (CERCLA)established a national program for responding to releases of hazardous substances into theenvironment. In anticipation of CERCLA, the Department of Defense (DOD) developed theInstallation Restoration Program (IRP) for response actions for potential releases of toxic orhazardous substances at DOD facilities. Like the U.S. Environmental Protection Agency’s(USEPA’s) Superfund Program, the IRP follows the procedures of the National Oil and HazardousSubstances Pollution Contingency Plan (NCP).

TABLE 2-1

PESTICIDES STORED AT HOMESTEAD AIR RESERVE BASE, FLORIDA

Vaponite 2EC chloropicrin

Wasp Freeze SA-77, Cide Kick

Ficam W (bendiocarb) Nalco-Trol

malathion 95% Dal-e-rad

Cynthion 57% Velpar

baygon strips Hyvar X (bromacil)

baygon 1.5% diquat

Dibrom (85% Naled) Aquazine (simazine)

Dursban Granules 0.5% (chlopyrifos) Balan

Dursban 4E Banvel 720

Inspector PT 565 Pramitol 5PS

Knox-out 2FM (Diazinon) paraquat

baygon bait Eptam 7-E

Precor 5E Round-Up (glyphosphate)

Talon-G Karmex (diuron)

Baytex AATREX

d-Phenothrin (spray cans) Promitol 25e

Nemacur Asulox

Seven (carbaryl) Dowpon (dalapon)

Keithane MF Dithane M-45

Dowfume MC-2 (methyl bromide) Fungo 50 (methyl thiophanate)

Phostoxin (aluminum phosphide) Tersan 1991 (benomyl)

Note: Capitalization of the first letter indicates that the name is a registered trademark.Source: Geraghty & Miller, Inc., 1992/Engineering Science, 1983

7

Homestead ARB was already engaged in the IRP Proram when it was placed on the National

Priorities List (NPL) on August 30, 1990. Cleanup of DOD facilities is paid for by the Defense

Environmental Restoration Account (DERA), which is DOD's version of Superfund.

The Superfund Amendment and Reauthorization Act (SARA), enacted in 1986, requires federal

facilities to follow NCP guidelines. The NCP was amended in 1990 (see 40 CFR 300 et seq.) to

implement CERCLA under SARA. In addition, SARA requires greater USEPA involvement and

oversight of Federal Facility Cleanups. On March 1, 1991, a Federal Facility Agreement (FFA) was

signed by Homestead ARB (formerly Homestead AFB), the USEPA, and the Florida Department of

Environmental Protection (FDEP). The FFA guides the remedial design/remedial action (RD/RA)

process.

The purpose of the FFA was to establish a procedural framework and schedule for developing,

implementing, and monitoring appropriate response actions at Homestead ARB in accordance with

existing regulations. The FFA requires the submittal of several primary and secondary documents for

each of the operable units at Homestead ARB. This ROD concludes all of the remedial

investigation/feasibility study (RI/FS) requirements for OU-7 and selects a remedy for the OU.

As part of the RI/FS process, Homestead ARB has been actively involved in the Installation

Restoration Program (IRP). From 1983 to 1992, 27 Potential Sources of Contamination (PSCs) were

identified at Homestead ARB. Ten sites have been investigated in the PA/SI stage of CERCLA, with

four sites warranting no further investigation and six sites requiring further investigation. One of the

PSCs sites has been closed under the Resource Conservation and Recovery Act (RCRA) guidelines

and seven sites were investigated under the FDEP petroleum contaminated sites criteria (Florida

Administrative Code (FAC) 62-770). Additionally, a RCRA Facility Investigation (RFI) has been

conducted to evaluate numerous solid waste management units (SWMUs) identified during the

RCRA Facility Assessment (RFA). A cleanup effort was initiated after Hurricane Andrew to prepare

the base for realignment. This included the removal of fuel storage tanks and oil/water separators.

Additional PSCs have been identified subsequent to 1992 as a result of investigations and/or

remediation of the base. The following PSC sites are currently in various stages of reporting under

the CERCLA RI/FS guidelines.

8

OperablePSC Name Unit No.Fire Protection Training Area 2 1Residual Pesticide Disposal Area 2Oil Leakage Behind the Motor Pool 4Electroplating Waste Disposal Area 5Aircraft Washrack Area 6Entomology Storage Area 7Fire Protection Training Area 3 8Boundary Canal 9Landfill LF-12 10Sewage Treatment Plant/Incinerator Ash Disposal Area 11Entomology Shop 12Landfill SS-22 13Drum Storage Area 14Hazardous Storage Bldg. 15Missile Site 16Hanger 793 17Construction Debris Landfill 18Bldg. 208 19Bldg. 618 Parking Lot 20#32, Bldg. 619 Parking Lot 21Bldg. 761/764 22Bldg. 814 25Bldg. 745 26Bldg. 268 & 268 A 27Bldg. 750 28Bldg.760 29

Operable Unit No. 3 PCB Spill, C.E. Storage Compound and OU-9 Boundary Canal have been

closed out with No Further Action Record of Decisions (ROD’s). Operable Units 1, 2, 4, and 6 have

been completed through the ROD stage requiring various levels of remedial action/remedial design.

OU-8 has been closed out under CERCLA with a No Further Investigation Decision Document and

has been transferred to investigation and oversight in accordance with the FAC 62-770 program. Two

Solid Waste Management Units, OU-23 and OU-24, have been closed out while three areas of

concern (AOC-1, AOC-3, and AOC-5) are

9

in the preliminary assessment phase of investigation. Figure 2-1 depicts the above-listed CERCLA

sites, as well as the FAC 62-770 fuel contaminated sites currently under investigation.

The Base Realignment and Closure (BRAC) Cleanup Plan currently incorporates both the IRP and

associated environmental compliance programs to support full restoration of the base.

2.3 INVESTIGATION HISTORY

2.3.1 IRP Phase I - Record Search

An IRP Phase I - Records Search was performed by Engineering Science, and is summarized in their

report, dated August 1983 (Engineering-Science, 1983). During the Phase I study, sites with the

potential for environmental contamination resulting from past waste disposal practices were

identified. Thirteen sites of potential concern were identified by reviewing available installation

records, interviewing past and present Base employees, inventorying wastes generated and handling

practices for these wastes, conducting field inspections, and reviewing geologic and hydrogeologic

data. In general, Phase I studies are used to determine if a site requires further investigation.

The thirteen identified sites were ranked using the Hazard Assessment Rating Methodology (HARM)

developed by JRB Associates of McLean, Virginia, for the USEPA. HARM was later modified for

application to the Air Force IRP. The following factors are considered in HARM: (1) the possible

receptors of the contaminants; (2) the characteristics of the waste; (3) potential pathways for

contaminant migration; and (4) waste management practices. HARM scores for the sites ranked at

Homestead ARB ranged from a high of 72 to a low of 7 out of 100. Eight of the thirteen sites were

determined to have a moderate-to-high contamination potential, one of which was the Entomology

Storage Area. These sites were recommended for additional monitoring. The remaining five sites

were determined to have a low potential for environmental contamination.

According to the IRP Phase I Report, OU-7 received a moderate to high HARM score of 63 due to

the high hazard of wastes used and the high potential for contaminant migration via surface and

groundwaters of the site. Operable Unit 7 scored high as a potential migration pathway because of

the extremely permeable nature of the soils and underlying rock in the area and the proximity of the

drainage canal bordering the Civil Engineering Storage

10

Compound site. The Phase I report recommended collecting five soil/bedrock samples, performingwater extraction of them, and analyzing the extract for pH, 2,4,5-TP, Chlordane, DDT and itsmetabolites, and non-phosphate radical of carbaryl (Sevin).

2.3.2 IRP Phase II - Confirmation/Quantification

An IRP Phase II study was performed by Science Applications International Corporation, and areport was completed in March 1986 (SAIC, 1986). The objectives of Phase II were to confirm thepresence or absence of contamination, quantify the extent and degree of contamination, and todetermine the necessity to conduct remedial actions. During the Phase II study, additionalinvestigations were performed at the eight sites recommended for monitoring in the Phase I report,as well as two of the other thirteen originally-identified sites. Operable Unit 7 was included in thisinvestigation.

During the Phase II investigation, two shallow monitoring wells (I-15 and I-16) were installed at thesite (Figure 2-2). Groundwater samples were collected and analyzed for 17 specific pesticides,including insecticides and herbicides (Table 2-2). None of these pesticides were detected at levelsabove their respective detection limits. A complete discussion of the methods and the results of thestudy are detailed in the Phase II - Confirmation/Quantification Report (SAIC, 1986).

The Phase II report recommended that no additional work be performed at the site except forperiodic monitoring of the two wells (1-16, HS-16) located at OU-7.

2.3.3 IRP Phase III - Technology Base Development

The IRP Phase III is a research phase and involves technology development for an assessment ofenvironmental impacts. There have been no Phase III tasks conducted at the site to date.

2.3.4 IRP Phase IV - Additional Investigations

2.3.4.1 IRP Phase IV-A. The IRP Phase IV investigations consist of two areas of work activity.Phase IV-A involved additional site investigations necessary to meet the Phase II objectives, a reviewof all management methods and technologies that could possibly remedy site problems, andpreparation of a baseline risk assessment to address the potential hazards to human health and theenvironment associated with the constituents detected at the site.

SS6RIT.2-2

TABLE 2-2ANALYTICAL RESULTS OF GROUNDWATER SAMPLES

COLLECTED DURING PHASE II INVESTIGATIONSAT OU-7, ENTOMOLOGY STORAGE AREA

Homestead Air Reserve Base, FloridaSAIC, 1984

LOCATIONCONSTITUTENTS I-15 I-16PESTICIDES ug/L

Aldrin <0.02 <0.02DDD <0.02 <0.02DDT <0.02 <0.02Dieldrin <0.02 <0.02Endrin <0.02 <0.02Heptachlor <0.02 <0.02Heptachlor Epoxide <0.02 <0.02Lindane <0.01 <0.01Methoxychlor <0.20 <0.20Toxaphene <1.00 <1.00Diazinon <0.02 <0.02Malathion <0.10 <0.10Parathion <0.02 <0.022,4-D <0.06 <0.062,4,5-T <0.06 <0.062,4,5-TF (Silvex) <0.06 <0.06Sevin <1.00 <1.00

Source: Geraghty & Miller, Inc., 1992

11

Detailed alternatives were developed and evaluated, and a preferred alternative was selected. Thepreferred alternative was then described in sufficient detail to serve as a baseline document forinitiation of Phase IV-B.

2.3.4.2 1988 Investigation. The Phase IV 1988 field investigation included the collection andanalysis of seven surface-soil samples (SFS- 1 through SFS-7) from the top four inches of the soilprofile (Figure 2-3). Surface-soil sample SFS-1 was collected from outside the fenced compound nearBuilding 220 to establish background concentrations. These samples were analyzed fororganochlorine pesticides, chlorinated herbicides, volatile organic compounds (VOCs), base/neutraland acid extractable compounds (BNAs), and total Resource Conservation and Recovery Act(RCRA) metals (Table 2-3). Arsenic, barium, chromium, and lead were detected in all seven samples.Additionally, cadmium and mercury were detected in SFS-4 and SFS-7 and mercury was alsodetected in sample SFS-l. Six of the seven samples contained quantifiable concentrations of pesticidesincluding beta-BHC; delta-BHC; 4,4'-DDE; 4,4'-DDD; 4,4-DDT; and technical chlordane.Surface-soil samples SFS-1 (the background sample) and SFS-7 contained detectable concentrationsof polynuclear aromatic hydrocarbons (PAHs). In 1988, groundwater samples were collected fromtwo wells, 1-16 and HS-16, and analyzed for VOCs, BNAs, total recoverable petroleumhydrocarbons (TRPH) and total lead (Table 2-4). An estimated concentration of lead (1.6 microgramsper liter µg/L]), was detected in HS-16. Field parameters of pH, conductivity, temperature, andappearance/odor were measured during sampling and are presented in Table 2-5.

2.3.4.3 1989 Investigation. Sixteen shallow (approximately 6 feet below land surface [ft blsj) soilborings (P2-SS1 and P2-SB1 through P2-SB15) were drilled during the Phase IV 1989 fieldinvestigation (Figure 2-4). Continuous split-spoon samples were collected and screened for organicvapor concentrations using an organic vapor analyzer (OVA) and a total ionization potential (TIP)meter (Table 2-6). The highest organic vapor concentration of 900 parts per million (ppm) wasmeasured in the four to six foot bls interval sample collected from soil boring P2-SB8. This samplewas collected near the groundwater interface and may represent groundwater contamination.

Following the OVA screening, the shallow (0 to 2 ft b1s) and deep (2 to 4 ft b1s) split-spoon intervalswere retained in thirteen of the sixteen soil borings for chemical analysis. These samples wereanalyzed for BNAs, organochlorine pesticides, total metals, and C8-C20 hydrocarbons (Table 2-7).Detectable concentrations of PAHs were found in four (P2-SB5, P2-SB9, P2-SB10, and P2-SB11)of the thirteen soil samples. Various degrees of

TABLE 2-3ANALYTICAL RESULTS OF PHASE IV SOIL/BEDROCK SAMPLES COLLECTED IN 1988

AT OU-7, ENTOMOLOGY STORAGE AREAHomestead Air Reserve Base, Florida

Geraghty & Miller, 1988LOCATION

CONSTITUENTS 1/ SFS-1 2/ SFS-2 SFS-3LOCATION

SFS-4 SFS-5 SFS-6 SFS-7

Volatile Organics (ug/kg) ND ND ND ND ND ND ND

Base/Neutral and Acid Extractable Organics(ug/kg)Benzo(a)anthracene [714] <556 <538 <1,060 <602 <5,500 [560]Benzo(a)pyrene [735] <556 <538 <1,060 <602 <5,500 <1,110Benzo(b)fluoranthene [749] <556 <538 <1,060 <602 <5,500 [698]Benzo(g,h,i)perylene <1,160 <556 <538 <1,060 <602 <5,500 2,100Benzo(k)fluoranthene [849] <556 <538 <1,060 <602 <5,500 [540]Chrysene [1,000] <556 <538 <1,060 <602 <5,500 [513]bis(2-ethylhexyl)phthalate <1,160 <556 967 <1,060 <602 <5,500 <1,110Fluoranthene [1,150] <556 <538 <1,060 <602 <5,500 [531]Naphthalene <1,160 <556 <538 <1,060 <602 <5,500 1,420Phenanthrene [602] <556 <538 <1,060 <602 <5,500 1,560Pyrene [1,020] <556 <538 <1,060 <602 <5,500 [624]

Organochlorine Pesticides (ug/kg)Beta-BHC <37 <65 <320 <320 204 <33,000 <13,000Delta-BHC <37 [20] <320 <320 160 <33,000 <13,0004,4'-DDE [58] [54] 730 1,300 590 70,000 [26,000]4,4'-DDD [30] [94] 5,400 3,400 1,000 83,000 52,0004,4'-DDT 250 [52] 6,300 1,800 2,100 1,600,000 140,000Technical Chlordane [300] [590] <3,200 9,000 6,000 <33,000 <13,000

Chlorinated Herbicides (ug/kg) ND ND ND ND ND ND ND

Total metals (mg/kg)Arsenic 11 4.3 3.0 17 96 4.6 23Barium 320 229 66 21 14 17 24Cadmium <0.19 <0.15 [0.19] 0.83 <0.19 <0.18 0.67Chromium 16 12 7.8 40 27 8.3 14Lead 174 80 46 222 78 53 69Mercury 0.063 <0.022 <0.022 0.27 [0.029] <0.024 0.052

Source: Geraghty & Miller, Inc., 1992Explanation:1/ Constituents not detected in any samples are in an analyte group not shown.2/ Surficial soil samples were collected within 0 to 4 inches below land surface.[ ] Value is between level of quantitation and instrument detection limit.ND Not detected. None of the constituents in this group were detected above their respective detection limits.Shading denotes sample collected from soils later excavated and removed during 1994 Interim Removal Action(data no longer representative of site conditions).

SS7RI.T.1-4

TABLE 2-4ANALYTICAL RESULTS FOR PHASE IV GROUNDWATER SAMPLES

COLLECTED IN 1988 AT OU-7, ENTOMOLOGY STORAGE AREAHomestead Air Reserve Based, Florida

Geraghty & Miller, 1988

Constituents 1/ I-16 HS-16

Volatile Organic Compounds (ug/L) ND ND

Base/Neutral Extractable Compounds (ug/L) ND ND

TRPH (mg/L) 2/ <0.20 <0.20

Total Lead (ug/L) <1.0 [1.6]

Source: Geraghty & Miller Inc., 1992ND Not detected. None of the constituents in this group were detected above

their respective detection limits.

1/ Constituents not detected in any samples in an analytical group are not shown.2/ Total recoverable petroleum hydrocarbons.

SS7RI.T.1-5

TABLE 2-5RESULTS OF FIELD ANALYSES OF PHASE IV GROUNDWATER SAMPLESCOLLECTED IN 1988 AND 1989 AT OU-7, ENTOMOLOGY STORAGE AREA

Homestead Air Reserve Base, FloridaGeraghty & Miller, 1988 & 1989

SampleLocation

DateSample

pH(standard units)

Conductivity(umhos/cm)

Temperature(degrees Centigrade)

Appearance/Odor

HS-16 3/1/88 6.96/6.98 370/380 25.1 Clear/NoneI-16 3/1/88 7.55/7.48 350/350 25.1 Slightly Turbid/Slight

P2-MW1 4/25/89 6.8 600 25.7 Clear/StrongI-15 4/24/89 6.8 520 25.2 Clear/Slight1-16 4/24/89 6.8 420 25.1 Slightly Turbid/None

SP4-MW5 4/24/89 6.7 540 25.2 Clear/ModerateSource: Geraghty & Miller, Inc., 1992

TABLE 2-6RESULTS OF ORGANIC VAPOR ANALYSES OF PHASE IV SOIL/BEDROCK SAMPLES

COLLECTED IN 1989 AT OU-7, ENTOMOLOGY STORAGE AREAHomestead Air Reserve Base, Florida

Geraghty & Miller, 1989

ANALYSIS TIP (a) OVA (b) TIP OVA TIP OVASAMPLE DEPTH 0 - 2' 0 - 2' 2 - 4' 2 - 4' 4 - 6' 4 - 6'

BORING NUMBER Concentrations in parts per million (ppm)

SS1-PP2 (Background) 6.7 <1 3.2 <1 3.9 <1P2-SB1 0 <1 32.3 60 90 (c) 300 (c)P2-SB2 0.1 <1 0.1 <1 6.1 (c) <1 (c)P2-SB3 0.5 <1 0.7 <1 0.7 <1P2-SB4 0.2 <1 0.2 (c) <1 (c) 0.2 <1P2-SB5 18.9 <1 2.8 (c) <1 (c) 3.5 <1P2-SB6 2.6 <1 1.8 (c) <1 (c) 2.3 <1P2-SB7 1.7 <1 2.1 (c) <1 (c) 2.0 <1P2-SB8 2.5 <1 1.9 <1 385 (c) 900 (c)P2-SB9 (P2-MW1) 2.1 <1 119 25 89 (c) 50 (c)P2-SB10 0.8 <1 1.5 <1 1.8 <1P2-SB11 1.0 <1 0.8 <1 2.1 <1P2-SB12 2.0 <1 1.3 <1 1.1 <1P2-SB13 0.7 <1 1 (c) <1 (c) 1.2 <1P2-SB14 0.9 <1 1.9 <1 15.3 4P2-SB15 1.2 <1 2.6 <1 12.1 <1

EXPLANATION:

Shading denotes sample collected from soils later excavated and removed during 1994 Interim Removal Action (data no longer representative ofsite conditions).(a) Total ionizables present measured with a photoionization detector.(b) Organic Vapor Analyzer measured with a flame ionization detector.(c) Sample collected from depth interval partially excavated during 1994 Interim Removal Action (data may still be valid).

Source: Geraghty & Miller, Inc. 1992

PAGE 1 OF 2

TABLE 2-7ANALYTICAL RESULTS OF PHASE IV SOIL/BEDROCK SAMPLES COLLECTED IN 1989

AT OU-7, ENTOMOLOGY STORAGE AREAHomestead Air Reserve Base, florida

Geraghty & Miller, 1989LOCATION P2SB-1 P2SB-2 P2SB-3 P2SB-4 P2SB-5 PWSB-6 P2SB-7

S 2/ D 3/ S D S D S D 6/ S D 6/ S D 6/ S D 6/CONSTITUENTS 1/

Base/Neutral and Acid Extractable Organics (ug/kg)Acenaphthene <602 <641 <602 <602 <581 <602 <562 <610 <610 <649 <617 <549 <602 <617Acenaphthylene <602 <641 <602 <602 <581 <602 <562 <610 <610 <649 <617 <549 <602 <617Anthracene <602 <641 <602 <602 <581 <602 <562 <610 <610 <649 <617 <549 <602 <617Benzo(a)anthracene <602 <641 <602 <602 <581 <602 <562 <610 [541] <649 <617 <549 <602 <617Benzo(a)pyrene <602 <641 <602 <602 <581 <602 <562 <610 <610 <649 <617 <549 <602 <617Benzo(b)fluoranthene <602 <641 <602 <602 <581 <602 <562 <610 <610 <649 <617 <549 <602 <617Benzo(g,h,i)perylene <602 <641 <602 <602 <581 <602 <562 <610 <610 <649 <617 <549 <602 <617Benzo(k)fluoranthene <602 <641 <602 <602 <581 <602 <562 <610 <610 <649 <617 <549 <602 <617Chrysene <602 <641 <602 <602 <581 <602 <562 <610 646 <649 <617 <549 <602 <617Di-n-butylphthalate [572] 5/ 662 5/ [305] 5/ 606 5/ 1,010 5/ <602 [466] 5/ 677 4/ 759 <649 637 <549 <602 <617Bis(2-Ethylhexyl)phthalate <602 <641 <602 <602 <581 <602 <562 <610 2,270 5/ <649 <617 <549 <602 <617Fluoranthene <602 <641 <602 <602 <581 <602 <562 <610 <610 <649 <617 <549 <602 <617Fluorene <602 <641 <602 <602 <581 <602 <562 <610 <610 <649 <617 <549 <602 <617Ideno(1,2,3-cd)pyrene <602 <641 <602 <602 <581 <602 <562 <610 <610 <649 <617 <549 <602 <617Naphthalene <602 <641 <602 <602 <581 <602 <562 <610 <610 <649 <617 <549 <602 <617Phenanthrene <602 <641 <602 <602 <581 <602 <562 <610 952 <649 <617 <549 <602 <617Pyrene <602 <641 <602 <602 <581 <602 <562 <610 <610 <649 <617 <549 <602 <617

C8-C20 Hydrocarbons (total) (ug/kg) <11,900 <12,700 <11,900 <11,900 <11,500 <11,900 <11,100 <12,100 62,400 <12,900 <12,200 <10,900 44,200 <12,200

Organochlorine Pesticides (ug/kg)4,4'-DDE [770] [460] [2,900] 55 370 54 [990] 79 [140] <15 [1,400] [4.1] 580 <7304,4'-DDD <2,900 <1,500 [1,800] [13] 390 [6.6] <1,300 [6.9] 310 <15 3,800 [3.0] 6,400 <7304,4'-DDT 5,600 3,400 48,000 590 710 95 2,800 24 <290 <15 5,000 [7.8] 1,000 <730Endosulfan sulfate <2,900 <1,500 <7,200 <14 540 <14 <1,300 <15 <290 <15 <1,500 <3 <140 <730Endrin keton <2,900 <1,500 <7,200 <14 1,200 <14 <1,300 <15 330 <15 <1,500 <13 <140 <730alpha-Chlordane <14,000 <7,600 <36,000 <72 [74] [8.6] <6,700 <73 <1,500 <77 <7,400 <65 4,100 [940]gamma-Chlordane <14,000 <7,600 <36,000 <72 [69] [8.1] <6,700 <73 <1,500 <77 <7,400 <65 4,000 [950]Toxaphene <29,000 <15,000 <72,000 <140 <2,800 <140 <13,000 <150 <2,900 <150 <15,000 <130 <1,400 <7,300beta-BHC <1400 <760 <3600 <7.2 <140 <7.2 <670 <7.3 <150 <7.7 <740 <6.5 <72 <370

Total Metals (mg/kg)Antimony <2.8 <2.9 <2.9 <3.0 <2.7 <2.8 [3.1] <2.9 <2.8 <2.9 <2.8 <3.0 <2.8 <2.9Arsenic 4.3 2.7 26.0 2.2 3.7 1.6 35.0 <1.2 19.0 <1.2 20.0 15.0 18.0 8.2Barium [8.4] [7.9] [8.1] [5] [7.7] [4.5] [7.2] [4.0] [17] [4.0] [6.6] [5.7] [8.8] [4.9]Beryllium [0.15] <0.12 [0.22] <0.13 [0.12] 0.12 [0.14] <0.12 [0.16] <0.12 [0.12] <0.13 [0.14] <0.12Cadmium 0.81 <.60 <0.61 <0.64 <0.57 <0.59 <0.56 <0.60 <0.58 <0.60 <0.59 <0.63 <0.59 <0.60Chromium 11.0 9.6 15.0 4.7 8.0 5.2 12.0 4.5 9.4 3.7 4.9 3.4 11.0 3.8Copper 4.6 4.8 [2.1] <0.38 9.7 [1.8] 18.0 [0.5] 9.2 [0.41] 8.6 [0.5] 10.0 [1.3]Lead 194.0 173.0 22.0 20.0 7.7 3.1 57.0 <0.61 11.0 <0.61 3.3 <0.63 17.0 2.4Nickel [2.5] [2.0] [3.1] <1.3 [1.6] <1.2 [2.2] <1.2 [1.7] <1.2 <1.2 <1.3 [2.7] <1.2Thallium <17 21 <18 <19 <17 <18 <17 <18 <17 <18 <18 <19 <18 <18Zinc 95 81 35.0 13 5 [1.8] 14 0.51 22 [0.49] 3.6 [0.43} 21 2.5

1/ Constituents not detected in any samples in an analytical group are not shown.2/ Shallow (0-2 feet below land surface).3/ Deep (2-4 feet below land surface).4/ Below Instruments Detection Limit.5/ Constituent detected in lab blank.6/ Sample collected from depth interval partially excavated during 1994 Removal Action (data may still be valid).[ ] Value is between level of quantitation and instrument detection limit.Shading denotes sample collected from soils later excavated removed during 1994 Interim Removal Action (data no longer representative of site conditions).Source: Geraghty & Miller, Inc., 1992

PAGE 2 OF 2

TABLE 2-7ANALYTICAL RESULTS OF PHASE IV SOIL SAMPLES COLLECTED IN 1989

AT 08-7, ENTOMOLOGY STORAGE AREAHomestead Air Reserve Base, Florida

Geraghty & Miller, 1989LOCATION P-2SB-8 P-2SB-9 P2SB-10 P2SB-11 P2SB-12 SS1-P2 (BACKGROUND)

S D S D S D S D S D S DCONSTITUENTS 1/

Base/Neutral and Acid Extractable Organics (ug/kg)Acenaphthene <769 <625 <588 655 <607 <694 1,210 <556 <617 <633 <1,200 <641Acenaphthylene <769 <625 <588 <641 <607 <694 1,280 <556 <617 <633 <1,200 <641Anthracene <769 <625 <588 <641 <607 <694 2,050 <556 <617 <633 <1,200 <641Benzo(a)anthracene <769 <625 <588 <641 <607 <694 3,980 <556 <617 <633 <1,200 <641Benzo(a)pyrene <769 <625 <588 <641 <607 <694 2,440 <556 <617 <633 <1,200 <641Benzo(b)fluoranthene <769 <625 <588 <641 <607 <694 2,000 <556 <617 <633 <1,200 <641Benzo(g,h,i)perylene <769 <625 <588 <641 <607 <694 1,550 <556 <617 <633 <1,200 <641Benzo(k)fluoranthene <769 <625 <588 <641 <607 <694 2,140 <556 <617 <633 <1,200 <641Chrysene <769 <625 <588 <641 [374] <694 4,280 <556 <617 <633 <1,200 <641Di-n-butylphthalate [654] <625 <588 [378] [504] <694 <1,160 <556 <617 <633 <1,200 <641Bis(2-Ethylhexyl)phthalate <769 <625 <588 <641 2,630 5/ <694 <1,160 944 5/ <617 <633 <1,200 <641Fluoranthene <769 <625 <588 <641 <607 <694 4,880 <556 <617 <633 <1,200 <641Fluorene <769 <625 <588 892 <607 <694 2,770 <556 <617 <633 <1,200 <641Ideno(1,2,3-cd)pyrene <769 <625 <588 <641 <607 <694 2,230 <556 <617 <633 <1,200 <641Naphthalene [546] <625 <588 879 1,920 <694 2,610 <556 <617 <633 <1,200 <641Phenanthrene <769 <625 <588 1,970 837 <694 13,000 <556 <617 <633 <1,200 <641Pyrene <769 <625 <588 <641 <607 <694 7,930 <556 <617 <633 <1,200 <641

C8-C20 Hydrocarbons(total) (ug/kg) <15,200 <12,400 <11,600 687,000 37,100 <13,800 75,600 <11,000 <12,000 <12,500 <23,700 <12,700

Organochlorine Pesticides (ug/kg)4,4'-DDE [1,100] 31 5,400 [440] 370 [12] 2,000 [6.7] 1,000 [8.2] 4,200 434,4'-DDD 26,000 71 16,000 7,900 <140 [2.5] [960] [3.9] [270] <15 4,000 254,4'-DDT 83,000 64 66,000 11,000 240 17 6,200 29 1,800 [14] 12,000 190Endosulfan sulfate <1,800 <15 <1,400 <1,500 <140 <15 <1,400 <15 <300 <15 <1,400 <15Endrin keton <1,800 <15 <1,400 <1,500 <140 <15 <1,400 <15 <300 <15 <1,400 <15alpha-Chlordane <9,200 [13] [2,800] <7,700 <720 <75 <7,000 <74 [450] [38] [4,200] 89gamma-Chlordane <9,200 [9.2] [2,700] <7,700 <720 <75 <7,000 <74 [370] [34] [4,200] 90Toxaphene <18,000 670 <14,000 <15,000 <1,400 <150 <14,000 <150 <3,000 <150 <14,000 <150Beta-BHC <920 <7.4 <710 <770 <72 <7.5 <700 <7.4 <150 <7.5 <710 <7.6

Total Metals (mg/kg)Antimony <2.8 <2.8 <2.9 <2.7 <2.8 <2.9 <2.8 <2.9 <2.8 <3.0 [5.0] <3.3Arsenic 3.3 <1.2 12.0 5.0 47.0 8.2 41.0 <1.2 20.0 2.7 51.0 1.5Barium [8.1] [4.0] [5.0] [5.2] [11] [4.7] 38.0 [4.7] [8.5] [5.6] [20] [6.2]Beryllium <0.12 <0.12 <0.12 <0.11 [0.22] [0.13] [0.19] <0.12 [0.13] <0.12 [0.47] <0.24Cadmium <0.59 <0.59 <0.60 <0.56 <0.58 <0.60 <0.57 <0.61 <0.60 <0.63 1.4 <0.48Chromium 4.8 2.7 4.1 3.8 14.0 3.3 6.8 3.1 10.0 4.5 18.0 4.7Copper [1.6] <0.36 [0.55] [0.59] 3.0 [0.54] 6.50 <0.36 3.4 <0.38 36.0 4.4Lead 4.9 <0.59 <0.60 0.77 13.0 <0.60 14.0 <0.61 16.0 <0.63 37.0 <0.50Nickel [1.3] <1.2 <1.2 <1.1 [2.3] <1.2 [1.7] <1.2 [2.2] [1.5] [2.4] <1.5Thallium <18 <18 <18 <17 <17 <18 <17 <18 <18 <19 <7.8 <8.1Zinc 9.8 [0.33] [1.4] 2.5 9.1 [0.43] 10 [0.46] 12 [0.73] 38 3.4

1/ Constituents not detected in any samples in an analyti2/ Shallow (0-2 feet below land surface).3/ Deep (2-4 feet below land surface).4/ Below Instruments Detection Limit.5/ Constituent detected in lab blank.6/ Sample collected from depth interval partially excava[ ] Value is between level of quantitation and instrumentShading denotes sample collected from soils later excavaSource: Geraghty & Miller, Inc., 1992

12

organochlorine pesticide and heavy metal contamination were found in all of the soil samples.

Soil boring P2-SB9 was converted to a shallow (approximately 13 ft b1s) monitoring well (P2-MW1)(Figure 2-4). The groundwater from this well, the existing wells (I-15 and I-16), and a backgroundwell (SP4-MW5) were sampled and analyzed for BNAs, organochlorine pesticides, and total C8-C20

hydrocarbons (Table 2-8). No detectable concentrations of BNAs were found in these samples. Thepesticides that were quantifiable, 4,4'-DDE, 4,4'-DDD, 4,4'-DDT, alpha chlordane and betachlordane, ranged in concentration from 0.19 µg/L to 2.0 µg/L. The groundwater sample fromP2-MW1 was the only sample with a detectable concentration of C8-C20 hydrocarbons (156 µg/L).

In 1989, a topographic survey was conducted at OU-7. The survey was referenced to the NationalGeodetic Vertical Datum of 1929 (NGVD). The location and measuring point elevation of eachpermanent monitoring well was determined. A water-level survey from the permanent t monitoringwells indicates that no hydraulic gradient is present and that the potential for downward migrationof constituents is minimal.

2.3.5 1991 Remedial Investigation

In 1991, an RI was conducted at OU-7 by G&M. During the 1991 investigation, 15 surface and 15subsurface soil/bedrock samples were collected from soil borings P2-SL-0016 through P2-SL-0030(Figure 2-5). All soil/bedrock samples were analyzed for organochlorine pesticides. The soil/bedrocksamples from three borings (P2-SL-0022, P2-SL-0023, and P2-SL-0028) were additionally analyzedfor target compound list (TCL) VOCs, TCL, BNAs, and target analyte list (TAL) metals. The resultsof these analyses are discussed in Section 2.6.1.3.

Groundwater samples were collected from I-15, I-16, HS-16, and P2-MW1 and analyzed for TCLVOCs, BNAs, TAL metals, organochlorine pesticides, and TRPH (Figure 2-5). Additionally, thegroundwater sample collected from HS-16 was analyzed for total dissolved solids (TDS).Groundwater samples collected from four monitoring wells (SP10-MW-0003 throughSP10-MW-0006) at Site ST-18 and two monitoring wells (SP4-MW4 and SP4-MW5) at Site SS-2were analyzed for volatile organic halocarbons, PAHs, benzene, toluene, ethylbenzene, and xylene(BTEX), methyl t-butyl ether (MTBE), 1,2-dibromoethane (EDB), total lead, and TRPH. Thegroundwater quality results from these monitoring wells were utilized in the characterization of OU-7in the 1991 investigation. Analytical

TABLE 2-8SUMMARY OF ANALYTICAL RESULTS FOR PHASE IV GROUNDWATER SAMPLES

COLLECTED IN 1989 AT OU-7, ENTOMOLOGY STORAGE AREAHomestead Air Reserve Base, Florida

Geraghty & Miller, 1988

LOCATION SP4-MW5CONSTITUENTS 1/ P2-MW1 I-15 1-16 (BACKGROUND)

Base/Neutral Extractable Compounds (ug/L ND ND ND ND

C8-C20 Hydrocarbons (total) (ug/L) 156 <100 <100 <100

Organochlorine Pesticides (ug/L)4,4'-DDE [0.062] <0.10 [0.051] 0.214,4'-DDD 1.5 <0.10 <0.10 0.194,4'-DDT 2.0 <0.10 [0.017] 0.98alpha-Chlordane [0.045] <0.50 [0.22] [0.19]gamma-Chlordane [0.025] <0.50 [0.15] [0.19]

EXPLANATION:

1/ Constituents not detected in any samples in an analytical group are not shown.ND Not detected. None of the constituents in this group were detected above their detection limits.[ ] Value is between level of quantitation and instrument detection limit.

Source: Geraghty & Miller, Inc., 1992

13

methodologies used for sample analysis in 1991 were those specified in USEPA SW 846. The resultsof these analyses are presented in Section 2.6.1.5. Complete results of the 1991 RI are presented inG&M’s report titled Remedial Investigation Report for Site SS-7 Entomology Storage Area (FormerSite P-2), Homestead AFB, Florida (G&M, 1992).

2.3.6 1993 Remedial Investigation Addendum

The purpose of the 1993 RI Addendum was to evaluate the current soil/bedrock and groundwaterquality at OU-7 with respect to the USEPA TCL/TAL employing Contract Laboratory Program(CLP) methodologies and documentation and to fill data gaps from the previous field investigations.

Three soil borings (P2-SL-0031, P2-SL-0032, and P2-SL-0033) (Figure 2-5) were advanced to thewater table. Two samples were collected from each borehole. All soil/bedrock samples were analyzedfor TCL organochlorine pesticides and PCBs and cyanide. The two samples from P2-SL-0031 wereadditionally analyzed for TCL VOCs, TCL BNAs, and TAL metals.

One new deep monitoring well (P2-DMW-0001) (Figure 2-5) was installed at 40 ft bls to determinevertical migration of contaminants. This new deep well was sampled as were four shallow monitoringwells (P2-MW1, I-15, I-16, and SP4-MW4). All groundwater samples were analyzed for TCLorganochlorine pesticides and PCBs and cyanide. Additionally, groundwater samples from wellsP2-MW-1 and P2-DMW-001 were analyzed for TCL VOCs, TCL BNAs, and TAL metals (total anddissolved).

Complete results of the 1993 RI are presented in Montgomery Watsons’ report titled RemedialInvestigation Report Addendum for Operable Unit Site SS-7, Entomology Storage Area (Former SiteSP-2), Homestead Air Reserve Base, Florida (MW, 1996).

2.3.7 1994 Investigation

In 1994, an Interim Removal Action (ERA) was conducted at OU-7 by IT under contract with theU.S. Army Corps of Engineers (USACE) Mobile District. The remedial activities included delineationand profiling of contaminated soil/bedrock, determination of appropriate soil disposal methods,excavation and disposal of contaminated soil/bedrock, and analysis of confirmation samples collectedfrom within the excavation limits. Also performed as part of the remedial activities was the disposalof miscellaneous debris and decontamination

14

materials from the site. Extensive sampling throughout the CE Storage Area and Pesticide StorageArea identified two areas with elevated arsenic and pesticide contaminated soils. The north excavationarea (North Area) consisted of a roughly circular area with a diameter of approximately 55 feet andan area of approximately 2,400 square feet. The south excavation area (South Area) was trapezoidalin shape and encompassed an area of approximately 12,300 square feet.

Prior to the removal of contaminated soilfbedrock from OU-7, limited delineation sampling wasperformed to provide additional information concerning the concentrations and extent of selectedcontaminants in the soil/bedrock. The OU-7 delineation sampling program included the collection ofsamples on a 50-foot grid between the North Area and the South Area (Figure 2-6). The soil/bedrocksamples were analyzed for total arsenic, and selected samples on the grid were also analyzed forpesticides. Additionally, samples were collected from the North Area to further define the limits ofarsenic and pesticide contamination.

In addition to the delineation sampling performed in the OU-7 area, profile samples were alsocollected to provide information for the completion of waste disposal profiles for off-site disposal ofcontaminated soil/bedrock. Since data collected during the profile sampling program were used tocharacterize soil/bedrock removed during the Interim Removal Action, that information is notsumniarized in this document. Further details on the profile sampling program are found in Sections3.0 and 4.0 of The Interim Action Report: Entomology Storage Area (SS-7), (IT, September 30,1994).

Upon completion of excavation activities, confirmatory samples were collected from the excavationlimits of the North and South Areas. Sampling locations are shown in Figures 2-7 and 2-8. The finalexcavation limits are presented on Figure 2-9. The samples were analyzed using CLP methodologiesfor total arsenic and/or TCL VOCs, TCL sernivolatile organic compounds, TCL pesticides/PCBs,TAL metals, and total cyanide. A summary of the confirmatory sampling results from areas notsubsequently excavated is presented in Section 2.6.1.3. A summary list of detected analytes and theircorresponding Removal Action Levels is provided in Table 2-9.

The soil/bedrock excavated from the ESA were transported to USPCI’s Clive, Utah, incinerationfacility for disposal. A total of 1,538 tons and 2,809 tons of soil were removed form the North andSouth Areas, respectively. According to USPCI representatives, incineration of the soils wasscheduled for January 1995, as part of a trial bum program associated with startup of the incineratorfacility. In addition, approximately 61 tons of

TABLE 2-9CONFIRMATION SAMPLING PARAMETERS

OU-7, ENTOMOLOGY STORAGE AREAHomestead Air Reserve Base, Florida

IT Corporation, 1994

Detected Parameter (a)

RemovalAction

Level (a) Detected Parameter (a)

RemovalAction

Level (a) Detected Parameter (a)

RemovalAction

Level (a) Detected Parameter (a)

RemovalAction

Level (a)

VOLATILES SEMI-VOLATILES PESTICIDES/PCBs METALSAcetone NL (b) Naphthalene 1 (e) alpha-BHC NL (b) Aluminum NL (b)Benzoic Acid NL (b) 2-Methylnaphthalene 1 (e) beta-BHC NL (b) Arsenic 3.16Bromomethane NL (b) Acenaphthene 1 (e) delta-BHC NL (b) Barium 2,750Chlorobenzene 0.050 (c) Dibenzofuran 1 (e) gamma-BHC (Lindane) NL (b) Beryllium NL (b)Methylene Chloride 42.2 Fluorene 1 (e) Aldrin NL (b) Calcium NL (b)Toluene 0.1 (d) Phenanthrene 1 (e) Heptachlor NL (b) Chromium 160Trichloromethane 0.050 (c) Acenaphthylene 1 (e) Heptachlor epoxide 0.101 Copper NL (b)Xylenes (total) 0.1 (d) Anthracene 1 (e) Dieldrin 0.269 Iron NL (b)

Carbazole 224 4,4'-DDE 12.4 Lead 108 (c)Di-n -butylphthalate NL (b) Endrin NL (b) Magnesium NL (b)

Fluoranthene 1 (e) Endosulfan II NL (b) Manganese NL (b)Benzo(a)anthracene 5.04 4,4'-DDD 17.5 Mercury 23 (c)

Butylbenzylphthalate 1.000 Endosulfan sulfate NL (b) Nickel 3.24Pyrene 1 (e) 4,4'-DDT 11.3 Potassium NL (b)

Chrysene 50.3 Methoxychlor NL (b) Selenium 389 (c)bis(2-Ethylhexyl)phthalate NL (b) Endrin ketone NL (b) Silver 165 (c)

Benzo(b)fluoranthene 5.01 Endrin aldehyde NL (b) Sodium NL (b)Benzo(k)fluoranthene 4.97 alpha-Chlordane 3.21 Vanadium NL (b)

Benzo(a)pyrene 0.504 gamma-Chlordane 3.21 Zinc NL (b)Indeno(1,2,3-cd)pyrene 5.04 Arochlor NL (b) OTHER PARAMETERSDibenzo(a,h)anthracene 0.505 Total Cyanide Not Reported

Benzo(g,h,i)perylene 1 (e)NOTES:

Source: Interim Action Report: Entomology Storage Area (SS-7). IT Corporation (September 30, 1994).Boldface values exceed the corresponding Removal Action Level value.(a) Unless otherwise indicated, values are shown in mg/kg units.(b) Not Listed. Analyte either was not listed on the February 15, 1994 FDEP “Soil Target Level” table; was listed but qualified with an “ND;” or was not listed in Chapter 62-775 of the FAC.(c) Analyte was not fined on the February 15, 1994 FDFP “Soil Target Level” table, but was listed in Chapter 62-775 of the FAC.(d) Analyte was not listed on the February 15,1994 FDEP “Soil Target Level” table. However, a maximum concentration of 100 ppb (0. 100 mg/kg) was lived in Chapter 62-775 of the FAC under “Total Volatile Organic Aromatics (VOA).”(e) Analyte was not listed on “Soil Target Level” table. However. a maximum concentration of 1 ppm (1 mg/kg) was lived in Chapter 62-775 of The FAC under “Polynuclear Aromatic Hydrocarbons (PAH).”(f) Not Detected.

15

debris were removed from the site prior to excavation and transported to USPCI’s Lone Mountainlandfill facility in Oklahoma for micro-encapsulation and final disposal in a hazardous waste landfill.The debris consisted of a variety of materials including wood, concrete, metal and plastic.Micro-encapsulation was perfonned by coating the debris with Portland cement grout prior tolandfilling.

The excavations created as a result of the IRA undertaken at OU-7 were backfilled with importedcrushed limestone fill material. Prior to import, the fill was analyzed to verify the lack of chemicalcontaminants. Samples of the fill material were analyzed for volatile organic aromatic hydrocarbons,chlorinated hydrocarbons, PAHs, total petroleum hydrocarbons, and TCLP chromium, lead, andcadmium. Field density testing was also performed after backfilling to verify compaction of thebackfill material.

As a result of the OU-7 IRA, 35 Soil Sampling points from previous investigations were excavatedand removed. Seven soil sample points from the 1989 G&M investigation and three sample pointsfrom the 1991 G&M investigation were collected at or below the IRA excavation limits. A summarylist of soil samples collected from the excavated areas, including sample identifiers and intervaldepths, is presented as Table 2- 10.

Delineation Sampling and Analysis. Prior to the removal of affected soils from the OU-7 area,limited delineation sampling was performed to provide additional information concerning theconcentrations and extent of selected contaminants in the soil/bedrock. The OU-7 delineationsampling program was performed in accordance with directions received by IT in a USACE-MobileDistrict letter dated February 3, 1994. The directions in the letter were based on recommendationsmade in the Engineering Evaluation Cost Analysis (EECA) and on requirements of the BaseConversion Team. The delineation sampling program included the collection of samples on a 50-footgrid between the North and South Areas of included excavation (Figure 2-6). The soil/bedrocksamples were analyzed for total arsenic according to EPA SW-846 Method 6010. Selected sampleson the grid were also analyzed for pesticides in accordance with EPA SW-846, Method 8080. Thedelineation analyses were performed in accordance with EPA SW-846 methodologies. In additionto the sampling program directed in the February 3, 1993 letter, samples were collected in the plannedNorth Area excavation to further define the limits of arsenic- and pesticide-affected areas.

The soil/bedrock samples were collected using split-spoon sampling procedures in accordance withmethods detailed in the project work plan. The soil/bedrock samples were composited from a depthof zero to approximately two feet below land surface (ft bls).

TABLE 2-10

SUMMARY OF SOIJJBEDROCK SAMPLES FROM EXCAVATED AREASOU-7, ENTOMOLOGY STORAGE AREA

Homestead Air Reserve Base, FloridaIT Corporation, 1994

Sample LocationDepth

Interval

IRAExcavation

Depth Investigation Comments

NORTH AREA (a)

P2-SS-1-2 0' - 2' 4' 1989 (Geraghty & Miller) Excavated (b)P2-SS-1-4 2' - 4' 4' 1989 (Geraghty & Miller) Excavated (b)

P2-SL-0017-2 0' - 2' 6' 1991 (Geraghty & Miller) Excavated (b)P2-SL-0018-2 0' - 2' 4' - 6' 1991 (Geraghty & Miller) Excavated (b)P2-SL-0017-4 2' - 4' 6' 1991 (Geraghty & Miller) Excavated (b)P2-SL-0018-4 2' - 4' 4' - 6' 1991 (Geraghty & Miller) Excavated (b)

ESA302/CH1; CH3 through CH5; CH7; CH8; CH12; and CH16 0' - 2' 6' 1994 (IT Corporation) Excavated (b)ESA302/CH2 and CH6 0' - 2' 4' 1994 (IT Corporation) Excavated (b)ESA302/CH11 0' - 2' 4' - 6' 1994 (IT Corporation) Excavated (b)ESA302/CH15 0' - 2' 3' 1994 (IT Corporation) Excavated (b)ESA302/CH17 0' - 2' 2' 1994 (IT Corporation) Excavated (b)ESA302/CH18 0' - 2' 2' - 3' 1994 (IT Corporation) Excavated (b)ESA302/CH9; CH10; CH13; CH14; and Delineation Points 1&2 0' - 2' (b,f) 1994 (IT Corporation) (b,f)

SOUTH AREA (a)

SFS-2 through -5 0' - 0.33' 3' 1988 (Geraghty & Miller) Excavated (b)SFS-6, SFS-7 0' - 0.33' 5' 1988 (Geraghty & Miller) Excavated (b)

P2-SB-1; -2; -8; -9; and -12 0' - 2' 5' 1989 (Geraghty & Miller) Excavated (b)P2-SB-4 through -7; -10; -11; and -13 0' - 2' 3' 1989 (Geraghty & Miller) Excavated (b)P2-SB-1; -2; -8; -9; and -12 2' - 4' 5' 1989 (Geraghty & Miller) Excavated (b)P2-SB-4 through -7; -10; and -11 2' - 4' 3' 1989 (Geraghty & Miller) PARTIAL REMOVAL (d)P2-SB-13 2' - 4' 1.5' - 3' 1989 (Geraghty & Miller) PARTIAL REMOVAL (d)

P2-SL-0022-2; P2-SL-0024-2 and P2-SL-0024-2 (c) 0' - 2' 3' 1991 (Geraghty & Miller) Excavated (b)P2-SL-0025-2 0' - 2' 1.5' - 3' 1991 (Geraghty & Miller) PARTIAL REMOVAL (d)P2-SL-0022-4 and P2-SL-0024-4 0' - 4' 3' 1991 (Geraghty & Miller) PARTIAL REMOVAL (d)P2-SL-0025-4 0' - 4' 1.5' - 3' 1991 (Geraghty & Miller) PARTIAL REMOVAL (d)P2-SL-0028-2 0' - 2' (g) 1991 (Geraghty & Miller) REMOVAL STATUS UNKNOWNP2-SL-0028-4 2' - 4' (g) 1991 (Geraghty & Miller) REMOVAL STATUS UNKNOWN

P2-SL-0031; and P2-SL-0031 (c) 0' - 1' 3' 1993 (Montgomery Watson) Excavated (b)P2-SL-0031 1' - 2' 3' 1993 (Montgomery Watson) Excavated (b)P2-SL-0033 0' - 2' 3' 1993 (Montgomery Watson) REMOVAL STATUS UNKNOWNP2-SL-0033 2' - 4' 3' 1993 (Montgomery Watson) REMOVAL STATUS UNKNOWN

ESA302/15; 19; 20; 23; through 25 0' - 2' 3' 1994 (IT Corporation) Excavated (b,f)ESA302/26 0' - 2' 5' 1994 (IT Corporation) Excavated (b,f)ESA302/27 0' - 2' 1.5' - 3' 1994 (IT Corporation) PARTIAL REMOVAL (e,f)ESA302/28 0' - 2' 3' 1994 (IT Corporation) Excavated (b,f)ESA302/CS34.1; and CS37.1 3' 3' 1994 (IT Corporation) Excavated (b)

NOTES:

(a) Area of excavation (1994 Interim Removal Action). (b) Interim Action Report: Entomology Storage Area (SS-7). IT Corporation (September 30, 1994) (c) QA/QC duplicate sample. (d) Sampling depth interval was not fully excavated. Analytical data associated with this sample may still be valid. (e) Limit of excavation lies over sampling point location. Analytical data associated with this sample may still be valid. (f) No data reported. (g) Soils from which ample was collected may have been excavated during die Site ST-18 underground storage tank (UST) removal action. Validity of analytical data associated with data sample is not known.

16

Confirmatory Sampling. Confirmation soil/bedrock samples were collected from the limits of theexcavation for analysis of TCL VOCs; TCL semivolatile organic compounds; TCL pesticides/PCBs;TAL metals; and total cyanide. The confirmation samples were analyzed using CLP methodologies.Each sample was initially analyzed for arsenic using expedited laboratory turnaround. Samples whichwere found to contain arsenic in concentrations below the approved action level of 15 mg/kg wereanalyzed for the full confirmation analytical program. Samples with arsenic concentrations greaterthan or equal to the approved action level indicated that further excavation was necessary. Theseareas were presented to the USACE-Mobile District for direction, with the general course of actionto be additional excavation. Additional information regarding the progress and delineation of theexcavation limits is provided in Section 2.3.7 of this ROD and the September 1994 IT Interim ActionReport: Entomology Storage Area (SS-7). Confirmatory sampling locations are presented in Figures2-7 and 2-8.

2.4 COMMUNITY RELATIONS HISTORY

The Remedial Investigation/Baseline Risk Assessment, Feasibility Study and Proposed Plan forHomestead ARB, OU-7 were released to the public in April 1996, November 1997, and November1997, respectively. These documents were made available to the public in both the administrativerecord and an information repository maintained at the Air Force Base Conversion Agency OL-Yoffice.

The public comment period was held from November 20, 1997 to December 22, 1997 as part of thecommunity relations plan for OU-7. Additionally, a public meeting was held on November 20, 1997at 7:00 p.m. at South Dade Senior High School. Public Notices were published in the Miami Heraldon November 16, 1997, and in the South Dade News Leader and The Courier on November 17,1997. At this meeting, officials from the U.S. Air Force Reserves and Dade County EnvironmentalResource Management (DERM), were prepared to discuss the Remedial Investigation, the BaselineRisk Assessment the Feasibility Study, and the Preferred Alternative for this OU as described in theProposed Plan and Record Of Decision. A court reporter was present at the meeting and prepareda transcript of the meeting. A copy of the transcript and all written comments received during thecomment period will be placed in the Administrative Record. A response to the comments receivedduring this period will be included in the Responsiveness Summary section of a later version of ROD.This decision document presents the selected remedial action for OU-7 at Homestead ARB, chosenin accordance with CERCLA, as amended by SARA and, to the

17

extent practicable, the National Contingency Plan. The decision on the selected remedy for the siteis based on the administrative record.

2.5 SCOPE AND ROLE OF RESPONSE ACTION

The U.S. Air Force, with concurrence from the FDEP and USEPA, has elected to define OperableUnit 7 as the former Entomology Storage Area and a large portion of the Civil Engineering StorageCompound found to have arsenic and pesticide contaminated soils. The remedial actions planned ateach of the operable units at Homestead ARB are, to the extent practicable, independent of oneanother. However, with respect to OU-3, OU-7, and FAC 62-770 Site ST-18, the close proximityof these areas has resulted in some physical overlap of site boundaries.

OU-3 was defined as the PCB spill area and associated potential PCB contamination only. This sitewas closed with a No Further Action ROD in 1994. Site ST-18 was regulated as a petroleumcontaminated site under FAC 62-770 and closed with a Contamination Assessment Report in 1993.As a result, any constituents other than PCBs at OU-3 and the FAC 62-770 mixed product analyticalgroup at ST-18 were evaluated as part of OU-7. This response action addresses the contaminationidentified at OU-7. Operable Unit 7 is located in the Cantonment Area retained by the Air ForceReserves and as such an industrial use scenario has been deemed appropriate for evaluating site risk.Under both the current and future industrial use scenario, the risk levels present at OU-7 are belowthe USEPA remediation-based benchmarks. This response action will be the final action at OU-7.This alternative offers a permanent solution for the site because the remnant pockets of contaminatedsoil have been capped, eliminating the risk to current and future base workers.

2.6 SUMMARY OF SITE CHARACTERISTICS

The former Entomology Storage Area is located in the west-central portion of the Facility. TheEntomology Storage Area was a fenced, sheltered area of approximately 0.13 areas in the southeastcorner of the Civil Engineering Storage Compound that was used in the 1960s as a storage area forbulk quantities of pesticide compounds. Diesel fuel was also reportedly stored in the southern portionof the site. The dates and quantities of pesticides and diesel fuel stored at the site are not available.Operable Unit 7 was later expanded to include a large portion of the Civil Engineering StorageCompound, A former petroleum contaminated site, Building 207 (Former Site ST-18) and OU-3(Former PCB Spill Area), increasing the total area to approximately 4 acres.

18

The OU-7 area has been retained by the 482nd Air Force Reserve as part of the cantonment area.

Expansion of this area by the Air Force Reserves included rebuilding as part of the new Base Supply,

Civil Engineering, and POL Operations area. Operable Unit 7 is now occupied by a new civil

engineering complex, three shops, a storage area, miscellaneous buildings and expanded parking

areas, and grassways.

2.6.1 Nature and Extent of Contamination

This section describes the nature and extent of contamination identified in the soil and groundwater

at OU-7. As discussed previously, the soils at OU-7 are relatively thin to absent. Where present, they

may be as much as 12-inches thick, with bedrock limestone the dominate feature exposed at the

surface. Because of the absence of a significant soil layer at the site, the term soil/bedrock has been

used to describe the media being sampled during the various investigations completed at this site.

The site has been characterized by evaluating the data obtained by G&M, Montgomery Watson, and

IT Corporation between 1991 and 1994. Soil/bedrock characterization was completed by evaluating

analytical results from the 1991 and 1993 RI samples that were not located within the IRA excavation

limits as well as the 1994 IRA delineation and confirmation samples that were not excavated during

removal activities. Data from samples locations excavated during the IRA were not considered

representative of current site conditions and were eliminated from site characterization activities.

Subsurface investigations at the site were initiated in 1986 by SAIC (SAIC, 1986). Further

soil/bedrock and groundwater investigations as part of the RI/BRA process were conducted by G&M

in 1988, 1989 and 1991 and by Montgomery Watson in 1993. RI/BRA activities were interrupted in

1994 when an IRA, completed by IT under the direction of the USACE-Mobile District, excavated

and disposal of arsenic and pesticide contaminated soil/bedrock from two areas at OU-7. Remedial

Investigation/Baseline Risk Assessment activities resumed at the conclusion of the IRA in 1994.

IT Corporation, under contract to the USACE-Mobile District, completed the delineation and IRA

program in 1994. Delineation soil/bedrock samples were obtained by IT from within the site limits

to determine excavation boundaries, as well as to provide waste disposal profiling information.

Excavation activities were restricted to two areas, a North Area, located adjacent to the former PCB

Storage Area, and a South Area, located at the site of the

19

pesticide storage yard. The North Area excavation was circular in shape with a surface area ofapproximately 2,400 sq. ft. The South Area was approximately trapezoidal in shape and encompassesan area of approximately 12,300 sq. ft. A total of 1,538 tons and 2,809 tons of soil/bedrock wereremoved from the North and South Areas, respectively, and disposed of in accordance with applicableregulations.

At the conclusion of the IRA, the site was re-evaluated in an RI/BRA to characterize the nature andextent of contamination subsequent to the removal activities. The IRA was not effective in removingsoil/bedrock contamination immediately adjacent to buildings or underlying asphalt paved areas. Asa result, four arsenic impacted (>15 mg/kg) areas remain on-site. However, the RI/BRA took intoaccount the fact that buildings, parking areas, or grassways now cover the site and have reducedpotential future direct and indirect exposures to the underlying soil/bedrock.

Site characterization activities evaluated data from 14 monitoring wells and 75 soil/bedrock samples.No groundwater samples have been collected from OU-7 subsequent to the IRA. However, pre-IRAgroundwater impacts indicated arsenic and pesticide contamination exists at moderate levels.Contaminants identified in the soil/bedrock subsequent to the IRA were primarily remnant pocketsof arsenic that were left in place due to their proximity to asphalt covered areas or buildings. ThePAHs identified in site soil/bedrock have been attributed to anthropogenic sources.

2.6.1.1 Summary of Soil/Bedrock Investigations

Seven surface soil/bedrock samples (SFS-1 through SFS-7), collected between 0 to 4 inches bgs,were collected at OU-7 during the 1988 installation restoration program (IRP) Phase IV investigationand analyzed for volatile organic compounds (VOCs), base/neutral and acid extractable compounds(BNAs), RCRA metals, organochlorine pesticides, and chlorinated herbicides. With the exception ofsample SFS-1, these sample locations were later excavated and removed during the 1994 IRA.

Then, in 1989, a Phase IV investigation was completed at OU-7 that included the completion of 15soil borings and the installation of one monitoring well. Soil samples were obtained from the 0-2 ftand 2-4 ft interval at each soil boring location, plus one background location. Soil borings completedduring this investigation were located within approximately 50 ft of the former pesticide storagebuilding. With the exception of SB-3, all these sample locations fall within the limits of the IRAexcavation and are not considered representative data points.

20

However, several of the 2-4 ft bgs samples may still be representative of site conditions, given thatthe sample collection depth may be greater than the excavation depth. A summary of soil/bedrocksample locations excavated during the IRA are provided in Table 2- 10.

Similarly, in 1991, G&M began a CERCLA RI sampling program for OU-7 that included thecompletion of 16 soil borings and the installation of three monitoring wells. Soil samples were againobtained from the 0-2 ft and 2-4 ft bgs interval from each soil boring location. Eleven of the soilboring locations during this investigation were installed at the perimeter of the storage compound todelineate the horizontal extent of contamination. Five of the soil borings were located north of theentomology storage compound, near the former OU-3 PCB Spill Area.

A total of 26 soil/bedrock samples were collected in 1991 for chemical analyses from the 0 to 2 ft blsinterval and the 2 to 4 ft bls interval bringing the total number of soil/bedrock samples collected aspart of the 1989 IRP Phase IV and 1991 CERCLA investigations to 52. The 1989 soil/bedrocksamples were designated as SB-1 through SB-15, and SS-1; and the 1991 soil/bedrock samples weredesignated as P2-SL-0016 through P2-SL-0030.

In 1993, Montgomery Watson performed an extended RI of the OU-7 site to fill data gaps fromprevious investigations. The Montgomery Watson investigation included the completion of threeborings (P2-SL-0031 through P2-SL-0033) and the collection of surface (0-1 or 0-2 ft bgs) andsubsurface (1 to 2 or 2 to 4 ft bgs) soil/bedrock samples from each boring. Samples were analyzedusing USEPA Contract Laboratory Program (CLP) protocols for Target Compound List (TCL)organochlorine pesticides/PCBs and cyanide. The samples from P2-SL-0031 were additionallyanalyzed for TCL VOCs, BNAs, and target analyte list (TAL) metals.

In 1994, an IRA was recommended for OU-7 to remove and properly dispose of arsenic and pesticidecontaminated soil/bedrock. Prior to completing the IRA, an engineering evaluation/cost analysis(EE/CA) was completed by the USACE to evaluate remedial alternatives while ensuring protectionto the public health or welfare and the environment. The IRA was performed in accordance withSection 300.415(b) of the National Contingency Plan (NCP) under CERCLA.

During the IRA, a 50-ft grid was established throughout the civil engineering storage compound.Soil/bedrock delineation samples were collected from selected locations and

21

analyzed for arsenic and pesticides. Two areas were identified for excavation activities, a North Areaand South Area.

During excavation activities confirmation samples were collected from the edges and floor of theexcavation to further define the contamination limits. The confirmation samples were initially analyzedfor total arsenic. Corrective Action Levels (CALs) for soil/bedrock removal activities wereestablished for chlordane, 4,4'-DDD; 4,4'-DDE; 4,4'-DDT; and arsenic based on Florida Health BasedSoil Target Levels for an excess cancer risk of 1E-06 for a general worker or for an industrialscenario. The arsenic CAL was subsequently revised by the Base Closure Team (BCT), which iscomprised of representatives from the USEPA, FDEP, Dade County Environmental ResourceManagement (DERM), USAF, and the USACE in April 1994, indicating that a higher (15 mg/kg)level would be acceptable for termination of the excavation activities. Samples that were found tocontain less than the 15 mg/kg arsenic action level were analyzed for TCL VOCs, TCL BNAs, TCLpesticides/PCBs, TAL metals, and total cyanide. However, remedial boundaries were primarilyestablished based on arsenic concentrations found in the floor and external sidewalls of the excavationas it progressed. A summary of the Corrective Action Levels (CALs) established for OU-7 areprovided in Table 2-11. However, as stated previously, four areas with elevated arsenicconcentrations (>15 mg/kg) were left in place due to proximity to buildings or asphalt covered areas.

Background Soil/Bedrock Concentrations. Early investigations at Homestead ARB delineatedsoil/bedrock contamination based on levels of constituents found in background samples collectedfrom throughout the base. Background levels at Homestead ARB for surface (0-2 ft bls) andsubsurface (2-4 ft and 4-6 ft b1s) soils/bedrock were presented in the OU-7 report prepared by G&M(G&M, 1992). Background levels were established based on the concentrations of constituents foundin soil/bedrock samples obtained from four CERCLA sites and one RCRA site at Homestead ARB.These values, as well as the common ranges of inorganic constituents found in soil/bedrock in theeastern U.S., the average value of inorganics found in carbonates and typical values of both organicand inorganic constituents found in uncontaminated soil/bedrock are shown in Table 2-12. Thesevalues were used in earlier studies in conjunction with the background boring P2-SL-0023 (199 1),as a basis for evaluating the OU-7 soil/bedrock samples.

TABLE 2-11

SUMMARY OFCORRECTIVE ACTION LEVELS

OU-7, ENTOMOLOGY STORAGE AREAHomestead Air Reserve Base, Florida

Chemical Corrective Action level1995

FDEP Health BasedSoil Target Levels

Chlordane 3.21 mg/kg1 3.00 mg/kg3

4,4'-DDD 17.5 mg/kg1 17.0 mg/kg3

4,4'-DDE 12.4 mg/kg1 11.0 mg/kg3

4,4'-DDT 11.3 mg/kg1 12.0 mg/kg3

Arsenic 15 mg/kg2 3.1 mg/kg3

1 Based on FDEP Soil Target Levels, Excess Cancer Risk of 1E-06 (General Worker)2 Revised April 1994 by BCT3 Revised FDEP Soil Target Levels, Excess Cancer Risk of 1E-06 (Industrial), September, 1995mg/kg Milligrams per kilogram

TABLE 2-12

BACKGROUND SOIL CONCENTRATIONSHomestead Air Force Base, Florida

Compound

AverageCarbonate

CompositionHem (1989)

Homestead AFBBackground

Soil(a)0-2 ft bls

Homestead AFBBackground

Soil(b)4-6 ft bls

Typical Valuesfor Uncontaminated

Soils (c)(mg/kg)

CommonRange (d)(mg/kg)

Average (d)(mg/kg)

Volatile Organic Compounds (µg/kg)Acetone 119.2Chlorobenzene 3.8Methylene Chloride 4

Total PAHs (µg/kg) 738.55 µg/kg 10 - 1300 forest (d)10 - 1000 rural60 - 5800 urban

8000-336,000 road dust

Base/Neutral and Acid Extractable Organic Compounds (µg/kg/dw)Acenaphthene NDBenzo(a)anthracene 67Benzo(a)pyrene 66Benzo(b)fluorantene 69Benzo(g,h,i)perylene 44Benzo(k)fluoranthane 66Bis(2-Ethylhexyl)phthalate 100Chrysene 79Dibenzofuran NDFluoranthene 52.4Fluorene ND2-Methylnaphthalene 84Naphthalene 50Phenanthrene 50Pyrene 49.151,2-Dichlorobenzene ND1,4-Dichlorobenzene ND

Total Phthalates (µg/kg) 126 515

Aluminum 8970 2400 425 100 ->10,000 57000Antimony -- <28 - 30 <7.4 - <160 0 - 30 2 - 10(f) - -(fag)Arsenic 1.8 1.6 <1.4 - <2.9 0 - 30 <0.1 - 73 7.4Barium 30 42.9 5 0 - 500 10 - 1,500 420Beryllium -- <2.8 - 2.9 <0.63 - <0.74 0 - 5 <1 - 7 0.85Cadmium 0.048 <2.8 - 3.0 <0.74 - <16 0 - 1 0.01 - 0.1(f) 0.06(f)Calcium 272,000 345,000 400,000 10 - 28,000 630Chromium >0.1 11.5 3.9 0 - 100 1 - 1,000 52Cobalt 0.12 <1.1 - 1.2 <1.3 - <1.5 7 <0.3 - 70 9.2Copper 4.4 <2.7 - 3.0 <3.2 - <3.7 30 <1 - 7,000 22Iron 8,190 1650 260 10 - 10,000 2,500Lead 16 4.05 1.4 0 - 500 <10 - 300 17Magnesium 45,300 1050 875 0 - 500 5 - 5,000 460Manganese 842 23 5.4 0 - 500 <2 - 7,000 640Mercury 0.046 0.014 <0.013 - <0.014 0 - 1 <0.01 - 3.4 0.12Nickel 13 <4.5 - 4.7 <5.1 - <5.9 15 <5 - 700 18Potassium 2,390 <110 - 120 <130 - <150 5 - 3,700 - -(g)Selenium -- <5.6 - 5.7 <2.9 - <7.1 0 - 1 <0.01 - 3.9 0.45Silver -- <1.1 - 1.2 <1.3 - <1.5 0.15 0.01 - 5.0(f) 0.05(f)Sodium 398 555 910 <500 - 50,000 7,800Thallium -- <1.1 - 5.6 <1.3 - <6.8 2.2 - 23 8.6Vanadium 13 <5.7 - 5.9 2.3 0 - 100 <7 - 300 66Zinc 16 20 <2.9 - 63 60 <5 - 2,900 5.2

(a) Source: Based on 5 background samples as reported in Geraghty & Miller, 1992.(b) Source: Based on 2 background samples as reported in Geraghty & Miller, 1992.(c) Source: Gas Research Institute, 1987.(d) U.S. Geologcal Survey Professional Paper 1270, Element Concentrations in Soils and Other Surficial Material of the Conterminous

United States Page 4, Table 1 (unless indicated otherwise).(e) Source: Manse, et al, 1992.(f) Data for these metals were not included in the USGS Paper. Concentrations were obtained from the USEPA

Office of Solid Waste and Emergency Response, Hazardous Waste Land Treatment, SW-974, April 1983, Page 273, Table 6.45.(g) Average not established.

22

2.6.1.2 Nature and Extent of Soil/Bedrock Contamination

The OU-7 RI/BRA completed by Montgomery Watson in May 1996 presented the analytical resultsfor soil/bedrock samples collected prior to, during, and subsequent to the 1994 IRA. However,characterization of the site regarding potential human and ecological health hazards were evaluatedbased on the concentration of IRA confirmation/delineation samples and previous soil/bedrocksamples that were not considered within the confines (vertically or horizontally) of the removalexcavation limits. The nature and extent of contamination found in the soil/bedrock of OU-7presented in this report focuses only on the locations deemed representative of the post IRA siteconditions. This consists of 75 samples of which 20 were collected during the 1991 G&M OU-7 RI,4 from the 1993 Montgomery Watson OU-7 RI, 2 from the 1993 Montgomery Watson OU-3 RI, and49 from the delineation/confirmation samples from the 1994 IT removal action. Results from thesamples considered representative of site conditions have been summarized and are presented in Table2-13. A more detailed discussion of the soil sampling methodologies and sample results from eachinvestigation can be found in the OU-7 Entomology Storage Area RI/BR (Montgomery Watson,1996a,b).

Volatile Organic Compounds. Fifty-one of the 75 soil/bedrock samples used to characterize the sitewere analyzed for VOCs. Of the 51 samples analyzed, there were none that contained concentrationsof a VOC that exceeded the FDEP Health Based Soil Target Levels or the Removal Action Levels.Six soil/bedrock samples had no detection of compounds above the method detection limit, whilemethylene chloride and/or acetone were identified in 29 of the 51 samples. Detections of methylenechloride and acetone compounds in soil samples from at Homestead ARB have been attributed tolaboratory or field decontamination artifacts and are not considered representative of site conditions.Xylene was detected above the method detection level in five soil/bedrock samples, each obtainedfrom within the North Area excavation. Concentrations of xylene ranged from 1.0 microgram perkilogram (ug/kg) to 200 ug/kg. Sample CSSB.1, also obtained from the North Area excavation, haddetectable concentrations of 1,1-dichlorethene (25 ug/kg), trichloroethene (19 ug/kg), toluene (23ug/kg), and chlorobenzene (19 ug/kg). Table 2-13 presents a summary of the VOC analytical results.Maps depicting the soil/bedrock sampling locations are provided in Figures 2-5, 2-6, 2-7, and 2-8.

23

Base/Neutral Acid Extractable Compounds. Fifty-one of the 75 soil/bedrock samples collected atOU-7 were analyzed for BNAs. Analytical results from these samples indicated detectableconcentrations of one or more of the following polynuclear aromatic hydrocarbons(PAHs);acenaphthylene, phenanthrene, anthracene, fluoranthene, pyrene, benzo(a)anthracene, chrysene,benzo(b)fluoranthene, benozo(k)fluoranthene, benzo(a)pyrene, indeno(1,2,3-c,d)pyrene,dibenz(a,h)anthracene, and benzo(g,h,i)perylene. Concentrations of total PAHs in soil/bedrocksamples ranged from 44 to 43,380 ug/kg. Twenty samples had total PAH levels greater than the1,000 ug/kg clean soil criteria (Florida Administration Code 62-775), benzo(a)pyrene was the onlyBNA compound that was detected above the 500 ug/kg FDEP Health Based Soil Target Level or the540 ug/kg Removal Action Level. Benzo(a)pyrene exceeded soil action levels in six soil/bedrocksamples with the maximum concentration being 4,300 ug/kg. Three of the soil/bedrock samplescontaining elevated benzo(a)pyrene were taken from confirmation samples in the South Area andthree were collected in the North Area. The PAHs in this area are likely the result of stormwaterrunoff and accumulation from anthropogenic sources such as roadways.

Di-n-butylphthalate, butylbenzylphthalate, and bis(2-ethylhexyl)phthalate were detected along withmany of the PAH compounds at concentrations less than the established Removal Action Levels inone or more confirmatory samples. In some instances, soil/bedrock BNA detection limits wereelevated to greater than the Removal Action Levels due to matrix interference. However, arsenic wasthe primary compound used for determining excavation lirnits.

Naphthalene or methylenaphthalene were detected in 4 soil/bedrock samples. One sample FCS4.5collected from the floor of the South Area excavation at a depth of 4.5 ft bgs, exceeded the RemovalAction Level for naphthalene (3.1 µg/kg), 2-methylnapthalene (8.1 µg/kg), acenaphthene (1.7 µg/kg),dibenzofuran (2.6 µg/kg), fluorine (3.4 µg/kg), phenanthrene (5.8 µg/kg), and anthracene (6.3µg/kg). Minimal exposure potential exist for this sample, given the fact it was collected from a depthof 5 ft bgs in bedrock. A summary of soil/bedrock analytical results for BNAs are presented in Table2-13. Maps depicting the soil/bedrock sampling locations are provided in Figures 2-5, 2-6, 2-7, and2-8.

Organochlorine Pesticides/PCBs. Seventy three of the 75 soil/bedrock samples used to characterizeOU-7 were analyzed for organochlorine pesticides and PCBs. Of the samples collected, none werefound to contain levels of pesticides which exceeded the FDEP Health Based Soil Target or theRemoval Action Levels. One sample, FCS7.5, collected from

24

bedrock at a depth of 5 ft bgs, contained 450 ug/kg of heptachlor which approaches the 500 ug/kgFDEP Health-Based Soil Target Level. In addition, four samples collected from the North Areaexcavation, contained a detectable levels of the PCBs aroclor 1260 at a concentration of 56 ug/kg.No Removal Action Levels were established for alpha-BHC, beta-BHC, delta-BHC, gamma-BHC(Lindane), aldrin, heptachlor, endrin, endosulfan II, endosulfan sulfate, methoxychlor, endrin ketone,endrin aldehyde, or PCBs.

Twenty pesticide compounds were detected in one or more of the soil/bedrock samples collectedfrom the North and South Areas. Compounds in detectable concentrations were alpha-BHC,beta-BHC, delta-BHC, gamma-BHC (Lindane), aldrin, heptachlor, heptachlor epoxide, dieldrin,4,4'-DD, 4,4'-DDD, 4,4'-DDT, Endrine, Endosulfan I, Endosulfan sulfate, Methoxychlor, Endrinketone, Endrin aldehyde, alpha-Chlordane, and gamma-Chlordane. A summary of the pesticide/PCBanalytical results is provided as Table 2-13. Soil/bedrock sampling locations are provided in Figures2-5, 2-6, 2-7, and 2-8.

Metals and Cyanide. Fifty-three of the 75 soil/bedrock samples used to characterize the site wereanalyzed for TAL metals. Cyanide was not detected in any of the samples collected. Of the metalsanalyzed, only arsenic and lead were detected at concentrations that exceeded Health Based SoilTarget or Removal Action Levels. Arsenic exceeded the Removal Action Levels of 15 mg/kg in 16samples with concentrations ranging from 16.7 mg/kg to 123 mg/kg. One of the samples thatexceeded arsenic removal levels was associated with the Site SS-13/OU-3, PCB Storage Areainvestigation. Arsenic concentrations in the North Area confirmation samples ranged from 3.5 to 44.5mg/kg and from 4.3 mg/kg to 47.3 mg/kg in the South Area samples. Those soil/bedrock samplelocations that exceed the present Corrective Action Level of 10 mg/kg include 22 soil/bedrock samplelocations; the two samples associated with the OU-3 sample location E-5, as well as 10 samples fromthe North Area and 10 samples from the South Area excavations. Arsenic was the primary constituentdetermining the IRA excavation limits. Those locations that contained concentrations of arsenic thatexceed Removal Action Levels are typically found in areas where the excavations could not beextended laterally due to the proximity to buildings or parking areas.

Lead was reported above action levels in soil/bedrock samples FCSN4.4 and CS37.1 atconcentrations of 114 mg/kg and 6,050 mg/kg, respectively. The 114 mg/kg concentration of leadis below the FDEP action level of 1,000 mg/kg but above the Removal Action Level of 108 mg/kg.The 6,050 mg/kg concentration of lead in sample CS37.1 appears to be an anomaly, as no apparentsource was identified.

25

Additional metals detected in soil/bedrock samples collected included aluminum, calcium, barium,beryllium, chromium, copper, cobalt, iron, magnesium, manganese, nickel, sodium, vanadium, zinc,and mercury (Table 2-13). These metals are typically present in carbonate rocks and soil/bedrock atvarious concentrations. According to average carbonate composition data presented by Hem (1989),calcium, magnesium, aluminum, iron, manganese, and sodium are the most common constituents ofcarbonates (Table 2-12). Additionally, barium, chromium, cobalt, copper, nickel, vanadium, zinc,mercury, and arsenic occur as trace concentrations. Concentrations of chromium, copper, arsenic,barium, calcium, sodium, and zinc were also reported in background sample P2-SL-0023-2 at levelsabove the average carbonate composition.

A summary of metal analytical results for soil/bedrock samples is provided in Table 2-13.Soil/bedrock sampling locations are provided in Figures 2-5, 2-6, 2-7, and 2-8.

2.6.1.3 Summary of Groundwater Investigations

Groundwater samples were collected from OU-7 monitoring wells during all phases of the IRPinvestigations with the exception of the 1994 IRA. Fourteen monitoring wells, ten in the South Areaand four in the North Area, have been used to evaluate groundwater impacts at OU-7. Four wells inthe South Area, SP-10-MW-0003 through SP-10-MW-0006, were associated with the former fuelssite ST-18, while the four wells in the North Area were associated with the former OU-3 PCB SpillSite or the fuels Site SS-2. Monitoring well locations are depicted in Figure 2-10.

The IRP Phase II investigation conducted in 1984 included the installation of two shallow monitoringwells (I-15 and I-16). Groundwater samples were collected and analyzed for 17 specific pesticides.None of these pesticides were detected at levels above their respective quantitation limits.

In 1991, groundwater samples were collected from ten permanent monitoring wells located at OU-7and adjacent sites. Groundwater samples collected from the monitoring wells at OU-7 (I-15, I-16,HS-16, and P2-MW1) were analyzed for TCL VOCs, BNAs, TAL metals, OC pesticides, and TRPH.The groundwater sample from HS-16 was additionally analyzed for TDS. The groundwater samplescollected from the monitoring wells SP10-MW-0003 through SP10-MW-0006 and the monitoringwells SP4-MW4 and SP4-MW5 were analyzed for volatile organic halocarbons, PAHs, benzene,toluene, ethylbenzene, and xylene (BTEX),

26

methyl tertiary butyl ether (MTBE), ethylene dibromide (EDB), total lead, and total recoverablepetroleum hydrocarbon (TRPH).

In 1993, Montgomery Watson performed an additional investigation of groundwater at OU-7 tofurther define the extent of contamination and to fill data gaps as recommended by the USEPA.Groundwater samples from the five monitoring wells (I-15, I-16, SP4-MW4, P2-MW1, andP2-DMW-0001) were analyzed for TCL organochlorine pesticides/PCBs and cyanide while thesamples from P2-MW1 and P2-DMW-0001 were additionally analyzed for TCL VOCs, BNAs, andtotal and dissolved (filtered) TAL metals.

Six groundwater monitoring wells, I-15, I-16, MW-5, P2-MW1, P2-DMW-0001, and SP4-MW4,were abandoned in accordance with the South Florida Water Management District policies. Theremaining wells are presumed to have been abandoned during construction of the new civilengineering complex. There have been no new wells installed at this site subsequent to constructionof the new Civil Engineering Compound.

2.6.1.4 Nature and Extent of Groundwater Contamination

Groundwater Quality and Guidance Concentrations. Groundwater from the Biscayne Aquiferis generally calcium-bicarbonate water and typically is classified as “hard”, but otherwise is ofgenerally acceptable chemical quality. However, dissolved iron concentrations are naturally high inthe Biscayne Aquifer System and commonly exceed the Florida Secondary drinking water regulationsstandard (Sonntag, 1987). Concentrations of inorganic of constituents detected in the BiscayneAquifer in Dade County are presented in Table 2-14. Groundwater analytical results were comparedto Florida Groundwater Guidance Concentrations, Florida 62-770 Target Clean-Up Levels, FederalUSEPA Primary and Secondary drinking-water standards’ Maximum Contaminant Levels (MCLs)and MCL goals (MCLGs) (Table 2-15).

Volatile Organic Compounds. 1991 Investigation. Groundwater samples were collected from 10permanent monitoring wells at OU-7. The OU-7 monitoring well samples were analyzed for TCLVOCs. No VOCs constituents were detected in the 1991 groundwater samples. A summary of the1991 groundwater analytical results are provided in Table 2-16.

1993 Investigation. One shallow (P2-MW1) and one deep (P2-DMW-0001) monitoring well weresampled for VOCs during the 1993 investigation. Groundwater samples from both wells werecollected in duplicate. No VOCs were detected in sample P2-MW1 and its

TABLE 2-14

CONCENTRATIONS OF DISSOLVED INORGANIC CONSTITUENTSDETECTED IN THE BISCAYNE AQUIFER IN DADE COUNTY, FLORIDA

Homestead Air Reserve Base, Florida

Constituent Range(mg/l)

Mean(mg/l)

Arsenic <0.001 -0.002 0.0012Barium <0.1 -0.1 0.1Cadmium <0.001 - 0.003 0.001Calcium 55 - 140 90Chloride 13 - 110 42Chromium (a) <0.01 - 0.01 --Fluoride 0.1 -0.5 0.2Iron <0.01 -1.9 0.56Lead <0.001 -0.006 0.0019Magnesium 1.7 - 19 5.6Mangnesium <0.01 -0.03 0.0097Mercury <0.0001 - 0.0003 0.0001Potassium 0.2 - 6.5 2.4Sodium 7.4 - 77 26.6Sulfate 0.1 - 45 14.6Zinc <0.01 - 0.03 0.0075

TDS 196 -478 333Alkalinity (as CaCO3) 157 - 624 263Hardness (as CaCO3) 150 -370 249

Source: Causaras, C.R., 1987, Geology of the Surficial Aquifer System ,Dade County,Florida. U.S. Geological Survey Water Resources Investigation Report 86-4126.

Notes:(a) All detected observations had the same value.TDS - Total Dissolved Solidsmg/l - milligrams per liter

TABLE 2-15

GROUNDWATER QUALITY CRITERIA

Analyte

FloridaDrinking

WaterStandards

Florida62-770

EPADrinking

WaterStandards

EPA MaximumContaminantLevel Goat

VOLATILE ORGANIC COMPOUNDS (ug/l)Bromodichloromethane NS NS 100 0Chloroform NS NS 100 0Dibromochloromethane NS NS NS NS

PESTICIDES/PCBS (ug/L)Alpha-BHC NS NS NS NSDDD NS NS NS NS

METALS (ug/L)Aluminum 2001 NS 50 TO 200 h NSArsenic 50 k NS 50* NSCadmium 5 k NS 5 i 5 iCalcium NS NS NS NSChromium 100 k NS 100 i 100 iLead 15 k 50 15 s 0Manganese 50 l NS 50 h NSVanadium NS NS NS NS

TOTAL RECOVER ABLEPETROLEUM HYDROCARBONS (mg/L) NS 5 NS NS

TOTAL DISSOLVED SOLIDS (mg/L) 500 l NS 500 h NS

BIOCHEMICAL OXYGEN DEMAND (mg/L) NS NS NS NS

TOTAL SUSPENDED SOLIDS (mg/L) NS NS NS NS

ALKALINITY (mg/L) NS NS NS NS

TOTAL ORGANIC CARBON (mg/L) NS NS NS NS

SULFATE (mg/L) 250 NS 500 500 g

SULFIDE (mg/L) NS NS NS NS

HARDNESS as CaCO3 (mg/L) NS NS NS NS

ug/L - micrograms per litermg/L - milligrams per literNS - No Standardg - Numbers represent EPA’s Primary MCL for Inorganics.h - Numbers represent EPA’s Secondary MCL for Inorganics which are non-enforceable taste, odor or appearance guidelines.i - Numbers represent EPA’s Final MCL effective July 1992, Federal Register, January 30, 1991 and July 1, 1991.k - Florida Primary Drinking Water Standard.l - Florida Secondary Drinking Water Standard.s - Final Action Level - The final lead action level is exceeded is the level of lead/copper in more than 10 percent* - Under Review

PAGE 1 OF 3

TABLE 2-16

SUMMARY OF ANALYTICAL RESULTS OF GROUNDWATER SAMPLESCOLLECTED IN 1991 AT OU-7, ENTOMOLOGY STORAGE AREA

Homestead Air Reserve Base, FloridaGeraghty & Miller, 1991

AnalyteFlorida

GroundwaterGuidance

Concentrations m

FAC62-770Florida

EPADrinking

WaterStandards

G&M Sample I.D.Savannah I.D.Sampling Date

Trip Blank37647-1011/24/91

P2-EB-002937647-111/24/91

P2-HS-1637647-211/24/91

P2-HS-901637647-3 11/24/91

P2-I-1537647-611/24/91

VOLATILE ORGANIC COMPOUNDS (ug/L):BenzeneMethylene chloride

15

k 1NS

b 5NS

e <<

5.05.0

<<

5.05.0

<<

5.05.0

UJ <<

5.05.0

UJ <<

5.05.0

UJ

BASE/NEUTRAL AND ACID EXTRACTABLEORGANIC COMPOUNDS (ug/l):

Acenaphthene 20 c NS NA < 10 < 10 < 10 [ 0.89]Benzo(a)pyrene 0.2 c 2 f NA < 10 < 10 [ 0.16] < 10bis-(2-Ethylhexyl)phthalate 6 NS NS f NA 54 320 UJ [1.7] U [2.6] UButylbenzylphthalate 1400 NS NS NA < 10 [ 0.50] J < 10 < 10Di-n-butylphthalate 700 NS NS NA < 10 [1.0] < 10 < 10Dibenzofuran NS NS NS NA < 10 < 10 < 10 < 10FluorantheneFluorene2-MethylnapthaleneNapthalenePhenanthrenePyrene

280280NS6.810

210

ccddcc

NSNSNSNSNSNS

NANANANANANA

<<<<<<

101010101010

<<<

[ 0.82]101010

[ 0 .69][ 0.64] J

<<<<

[ 0.55]10101010

[ 0.31] J

<<<

<<

101010

[ 0.95]1010

CHLORINATED PESTICIDES (ug/L):4,4'-DDD 0.1 NS NS NA < 0.020 < 0.020 UJ < 0.020 < 0.0204,4'-DDE 0.1 NS NS NA < 0.020 < 0.020 UJ < 0.020 < 0.020

METALS (ug/L):Aluminum 200 NS 50 to 200 h,i NA < 200 2900 J 4300 J 21000 JArsenic 50 k NS 50 g NA < 10 34 J 38 J 150 JBarium 2000 k NS 2000 i,g NA < 10 39 J 49 J 120 JCalcium NS NS NS NA 360 1300000 J 1700000 J 8900000 JChromium 100 k NS 100 i,g NA < 10 22 J 26 J 320 JCopper 1000 l NS 1300 s NA < 25 < 25 UJ < 25 UJ 26 JIron 300 l NS 300 h NA < 50 2000 J 2500 J 23000 JLead 15 k 50 15 s NA < 5.0 UJ 21 J 24 J 20 JMagnesium NS NS NS NA < 50 4200 J 5000 J 22000 JManganese 50 l NS 50 h NA < 10 38 J 48 J 880 JNickelPotassiumSodiumVanadiumZinc

100NS

16000049

5000 l

NSNSNSNSNS

100NSNSNS

5000

ff

h

NANANANANA

<<<<

4010005001024

< 401800

130001337

UJJJJUJ

< 401800

140001761

UJJJJUJ <

443600

28000120100

JJJJUJ

TOTAL PETROLEUM HYDROCARBONS (mg/L) NS 5 NS NA < 1.0 < 1.0 < 1.0 < 1.0

TOTAL DISSOLVED SOLIDS NS NS 500,000 h NA < 0.5 410 450 NA

PAGE 2 OF 3

TABLE 2-16

SUMMARY OF ANALYTICAL RESULTS OF GROUNDWATER SAMPLESCOLLECTED IN 1991 AT OU-7, ENTOMOLOGY STORAGE AREA

Homestead Air Reserve Base, FloridaGeraghty & Miller, 1991

Analyte

FloridaGroundwater

GuidanceConcentrations m

FAC62-770Florida

EPADrinking

WaterStandards

G&M Sample I.D.Savannah I.D.Sampling Date

P2-l-1637647-511/24/91

P2-MW-137647-511/24/91

SP10-MW-000337321-2 11/7/91

SP10-MW-000437292-4 11/6/91

SP10-MW-000537292-511/6/91

VOLATILE ORGANIC COMPOUNDS (µg/L):BenzeneMethylene chloride

15

k 1NS

b 5NS

e <<

5.05.0

<<

5.05.0

< 1.0NA

< 1.0NA

3.4NA

BASE/NEUTRAL AND ACID EXTRACTABLEORGANIC COMPOUNDS (ug/l):

Acenaphthene 20 c NS < 10 [5.3] < 10 < 10 < 10Benzo(a)pyrene 0.2 c 2 f < 10 < 10 < 10 < 10 < 10bis-(2-Ethylhexyl)phthalate 6 NS NS f [2.1] U [1.7] UJ < 10 < 10 < 10Butylbenzylphthalate 1400 NS NS < 10 < 10 < 10 < 10 < 10Di-n-butylphthalate 700 NS NS < 10 < 10 < 10 < 10 < 10Dibenzofuran NS NS NS < 10 [5.0] < 10 < 10 < 10Fluoranthene 280 c NS < 10 < 10 < 10 < 10 < 10Fluorene 280 c NS < 10 [9.9) < 10 < 10 < 102-Methylnapthalene NS d NS [0.30] J [34) < 10 < 10 < 10Napthalene 6.8 d NS [0.61] 12 < 10 < 10 < 10Phenanthrene 10 c NS < 10 15 < 10 < 10 < 10Pyrene 210 c NS < 10 < 10

CHLORINATED PESTICIDES (ug/L):4,4'-DDD 0.1 NS NS < 0.020 8.7 J NA NA NA4,4'-DDE 0.1 NS NS < 0.020 0.095 J NA NA NA

METALS (ug/L):Aluminum 200 NS 50 TO 200 h,i 3800 J 640 NA NA NAArsenic 50 k NS 50 g 29 J 960 NA NA NABarium 2000 k NS 2000 i,g 38 J < 10 NA NA NACalcium NS NS NS 2500000 J 370000 NA NA NAChromium 100 k NS 100 i,g < 50 UJ < 10 NA NA NACopper 1000 l NS 1300 s < 25 UJ < 25 NA NA NAIron 300 l NS 300 h 2500 J 630 NA NA NALead 15 k 50 15 s < 6.0 UJ < 5.0 UJ 230 12 140Magnesium NS NS NS 7700 J 2100 NA NA NAManganese 50 l NS 50 h 99 J 12 NA NA NANickel 100 NS 100 f < 40 UJ < 40 NA NA NAPotassium NS NS NS f < 1000 UJ 2000 NA NA NASodium 160000 NS NS 11000 J 13000 NA NA NAVanadium 49 NS NS < 50 UJ < 10 NA NA NAZinc 5000 l NS 5000 h < 100 UJ < 20 NA NA NA

TOTAL PETROLEUM HYDROCARBONS (mg/L) NS 5 NS < 1.0 14 < 1.0 < 1.0 < 1.0

TOTAL DISSOLVED SOLIDS NS NS 500,000 h NA NA NA NA NA

PAGE 3 OF 3

TABLE 2-16

SUMMARY OF ANALYTICAL RESULTS OF GROUNDWATER SAMPLESCOLLECTED IN 1991 AT OU-7, ENTOMOLOGY STORAGE AREA

Homestead Air Reserve Base, FloridaGeraghty & Miller, 1991

Analyte

FloridaGroundwater

GuidanceConcentrations m

FAC62-770Florida

EPADrinking

WaterStandards

G&M Sample I.D.Savannah I.D.Sampling Date

SP10-MW-900537292-2 11/6/91

SP10-MW-000637321-411/7/91

SP4-MW-437373-1011/11/91

SP4-MW-537401-5 11/12/91

VOLATILE ORGANIC COMPOUNDS (ug/L):BenzeneMethylene chloride

15

k 1NS

b 5NS

e 3.2NA

< 1.0NA

NA30.0 <

NA1.0

BASE/NEUTRAL AND ACID EXTRACTABLEORGANIC COMPOUNDS (ug/l):

Acenaphthene 20 c NS < 10 < 10 < 10 < 10Benzo(a)pyrene 0.2 c 2 f < 10 < 10 < 10 < 10Bis-(2-Ethylhexyl)phthalate 6 NS NS f < 10 < 10 < 10 < 10Butylbenzylphthalate 1400 NS NS < 10 < 10 < 10 < 10Di-n-butylphthalate 700 NS NS < 10 < 10 < 10 < 10Dibenzofuran NS NS NS < 10 < 10 < 10 < 10Fluoranthene 280 c NS < 10 < 10 < 10 < 10Fluorene 280 c NS < 10 < 10 < 10 < 102-Methylnapthalene NS d NS < 10 < 10 < 10 < 10Napthalene 6.8 d NS < 10 < 10 < 10 < 10Phenanthrene 10 c NS < 10 < 10 < 10 < 10Pyrene 210 c NS

CHLORINATED PESTICIDES (ug/L):4,4'-DDD 0.1 NS NS NA NA NA NA4,4'-DDE 0.1 NS NS NA NA NA NA

METALS (ug/L):Aluminum 200 NS 50 TO 200 h,i NA NA NA NAArsenic 50 k NS 50 g NA NA NA NABarium 2000 k NS 2000 i,g NA NA NA NACalcium NS NS NS NA NA NA NAChromium 100 k NS 100 i,g NA NA NA NACopper 1000 l NS 1300 s NA NA NA NAIron 300 l NS 300 h NA NA NA NALead 15 k 50 15 s 160 240 15 11Magnesium NS NS NS NA NA NA NAManganese 50 l NS 50 h NA NA NA NANickel 100 NS 100 f NA NA NA NAPotassium NS NS NS f NA NA NA NASodium 160000 NS NS NA NA NA NAVanadium 49 NS NS NA NA NA NAZinc 5000 l NS 5000 h NA NA NA NA

TOTAL PETROLEUM HYDROCARBONS (mg/L) NS 5 NS < 1.0 < 1.0 < 1.0 < 1.0

TOTAL DISSOLVED SOLIDS NS NS 500,000 h NA NA NA NA

27

duplicate sample P2-MW91. Acetone and chloroform were detected in sample P2-DMW-0001 atconcentrations of 4 µg/l and 2 µg/l, respectively. Chloroform, bromodichloromethane, anddibromochloromethane were detected in the duplicate sample P2-DMW-9001 at concentrations of9 µg/l, 4 µg/l, and 2 µg/l, respectively. All of these detection’s are qualified as estimated, becausethey where less than the CRQL. These compounds are classified as trihalomethanes with a regulatorylevel established in drinking water at <100 µg/l total concentration. Acetone and 1,2-dichloropropanewere detected in equipment blank P2-EB-0001 at concentrations of 11 µg/l and 2 µg/l, respectively.Neither of these two compounds were detected in the associated samples (P2-MW1 and duplicateP2-MW91). Methyl ethyl ketone and 1,2-dichloropropane were detected in equipment blank sampleP2-EB-0002 at concentrations of 4 µg/l and 3 µg/l, respectively. 1,2-dichloropropane was detectedin the associated sample duplicate, P2-DMW-9001. The source of these compounds is most likelythe isopropanol used for equipment decontamination.

A summary of constituents detected in groundwater during the 1993 investigation is provided asTable 2-17.

1994 Investigation. No groundwater samples were collected for analysis during the 1994 IRA.

Base/Neutral and Acid Extractable Compounds. 1991 Investigation. Several BNAs, mostlyPAHs, were detected in five of the ten groundwater samples, including one duplicate, collected atOU-7 in 1991, as shown in Table 2-17. Total PAHs were detected in samples I-15, I-16, HS-16,HS-9016 (the duplicate of HS-16), and P2-MW1 at concentrations of 1.84, 0.91, 1.46, 1.02, and 61.2µg/l, respectively. The FAC 62-770 regulations establish a 10 µg/l action level for total PAHs ingroundwater for petroleum contaminated sites. The aerial extent of groundwater containing PAHsabove 50 µg/l is limited to the southern portion of the site in the immediate vicinity of monitoring wellP2-MW1 (Figure 2-10). The naphthalene concentration of 54 µg/l detected in sample P2-MW1exceeded the Florida Groundwater Guidance concentration of 10 µg/l; however, none of the otherconcentrations of PAHs detected in the five groundwater samples exceeded Florida or FederalStandards for drinking water.

Additional BNAs (non-PAHs) detected in groundwater samples include di-n-butylphthalate detectedin sample HS-16 at a concentration of 1.0 µg/l; dibenzofuran was detected in sample P2-MW1 at aconcentration of 5.0 µg/l; and butylbenzylphthalate was detected in sample HS-16 at a concentrationof 0.50 µg/l. The concentrations of these non-PAHs detected were

PAGE 1 OF 4

TABLE 2-17SUMMARY TABLE OF DETECTED COMPOUNDS IN GROUNDWATER

OU-7, ENTOMOLOGY STORAGE AREAMONTGOMERY WATSON, 1993 INVESTIGATION

HOMESTEAD ARB, FLORIDA

Analyte

FloridaDrinking

WaterStandard

EPADrinking

WaterStandard

EPA MaximumContaminant

Level Goal

SampleID Date

Collected

P2-MW-13/3/93

P2-MW-91 3/3/93Duplicate

P2-DMW-0001 3/12/93

P2-DMW-9001 3/12/93

Duplicate

VOA TCL Compounds (ug/l)Acetone NS NS NS <10 <10 4 J <10Chloroform NS 100(a) NS <10 <10 2 J 9 JMethyl Ethyl Ketone (2-Butanone) NS NS NS <10 <10 <10 <10Bromodichloromethane NS 100(a) NS <10 <10 <10 4 J1,2-dichloropropane 5 5 0 <10 <10 <10 <10Dibromochloromethane NS 100(a) NS <10 <10 <10 2 J

Pesticide/PCB TCL Compounds (ug/l)Alpha BHC NS NS NS .030 JP 0.024 J <0.054 <0.055p,p’-DDE NS NS NS 0.12 0.090 J <0.11 <0.11p,p’-DDD NS NS NS 10 9.6 0.16 0.18 PP,p’-DDT NS NS NS .023 JP 0.022 J 0.078 J 0.11

BNA TCL Compounds (ug/l)2-Chlorophenol NS NS NS <11 <11 <11 3 J2-Methylnapthalene 10(b) NS NS 1 J 3 J 1 J 9 JAcenaphthene NS NS NS 4 J 3 J <11 <11Anthracene NS NS NS 2 J 2 J <11 <11Bis(20Ethylhexyl) Phthalate 6 6 0 1 J 1 J 0.2 J 1 JDi-n-Butyl Phthalate NS NS NS <11 <11 0.6J 2 JDibenzofuran NS NS NS 3 J 2 J <11 0.7 JDiethylphthalate NS NS NS <11 <11 <11 0.3 JFluoranthene NS NS NS 0.8 J 0.5 J <11 <11Fluorene NS NS NS 8 J 6 J <11 1 JN-Nitrosodiphenylamine NS NS NS <11 <11 0.8 J <11Napthalene 10(b) NS NS 2 J 2 J 0.9 J 7 JPhenanthrene NS NS NS 14 14 0.5 J 2 JPhenol NS NS NS <11 <11 4 J 35Pyrene NS NS NS 1 J 0.9 J <11 <11

All samples analyzed by Savannah Laboratories, Tallahassee, Florida Notes:< - not detected at specified detection limit B - compound detected in an associated blank (a) - MCL of 100 ug/L is for total THM'sNS - no standard J - estimated quantity, quality control criteria were not met (b) - total napthalenes must be <100 ug/l

to meet FAC 62-770 guidelines

PAGE 2 OF 4

TABLE 2-17SUMMARY TABLE OF DETECTED COMPOUNDS IN GROUNDWATER

OU-7, ENTOMOLOGY STORAGE AREAMONTGOMERY WATSON, 1993 INVESTIGATION

HOMESTEAD ARB, FLORIDA(CONTINUED)

Analyte

FloridaDrinking

WaterStandard

EPADrinking

WaterStandard

EPA MaximumContaminant

Level Goal

Sample IDDate Collected

SP4-MW43/3/93

P2-I-153/3/93

P2-EB-00013/3/93

P2-EB-00023/12/93

VOA TCL Compounds (ug/l)Acetone NS NS NS <10 <10 11 <10Chloroform NS 100(a) NS <10 <10 <10 <10Methyl Ethyl Ketone (2-Butanone) NS NS NS <10 <10 <10 4 JBromodichloromethane NS 100(a) NS <10 <10 <10 <101,2-dichloropropane 5 5 0 <10 <10 2 J 3 JDibromochloromethane NS 100(a) NS <10 <10 <10 <10

Pesticide/PCB TCL Compounds (ug/l)Alpha BHC NS NS NS <0.052 <0.055 <0.061 <0.052p,p’-DDE NS NS NS 0.044 J <0.11 <0.12 <0.10p,p’-DDD NS NS NS 0.019 J 0.23 <0.12 <0.10P,p’-DDT NS NS NS 0.075 J <0.11 <0.12 0.021 J

BNA TCL Compounds (ug/l)2-Chlorophenol NS NS NS NA NA <13 <112-Methylnapthalene 10(b) NS NS NA NA <13 <11Acenaphthene NS NS NS NA NA <13 <11Anthracene NS NS NS NA NA <13 <11Bis(20Ethylhexyl) Phthalate 6 6 0 NA NA <13 <11Di-n-Butyl Phthalate NS NS NS NA NA <13 <11Dibenzofuran NS NS NS NA NA <13 <11Diethylphthalate NS NS NS NA NA <13 <11Fluoranthene NS NS NS NA NA <13 <11Fluorene NS NS NS NA NA <13 <11N-Nitrosodiphenylamine NS NS NS NA NA <13 <11Napthalene 10(b) NS NS NA NA 0.3J <11Phenanthrene NS NS NS NA NA <13 <11Phenol NS NS NS NA NA 1J <11Pyrene NS NS NS NA NA <13 <11

All samples analyzed by Savannah Laboratories, Tallahassee, Florida Notes:< - not detected at specified detection limit B - compound detected in an associated blank (a) - MCL of 100 µg/L is for total THM’sNS - no standard J - estimated quantity, quality control criteria were not met (b) - total naphthalenes must be <100 ug/l

to meet PAC 62-770 guidelines

TABLE 2.17SUMMARY TABLE OF DETECTED COMPOUNDS IN GROUNDWATER

OU-7, ENTOMOLOGY STORAGE AREAMONTGOMERY WATSON, 1993 INVESTIGATION

HOMESTEAD ARB, FLORIDA(CONTINUED)

Analyte

FloridaDrinking

WaterStandard

EPADrinking

WaterStandard

EPAMaximum

Contaminant Level Goal

Sample IDDate

Collected

P2-MW-13/3/93

P2-MW-91

3/393

P2-MW-1

3/3/93Filtered

P2-MW-913/3/93

Filtered

P2-DMW-0001

3/12/93

P2-DMW-9001 3/12/93

Metals (ug/l)Aluminum 200(g) 50-200(c) NS 104 B 126 B <2.0 <20.0 39.7 B 48.7 BArsenic 50 (f) 50 (d) NS 534 540 510 632 <5.0W <15.0Barium 2,000 (f) 2,000 (d) 2,000 (g) 5.6 B 5.6 B 5.6 B 5.3 B 11.4 B 11.8 BCadmium 5(f) 5 (e) 5 5.4 5.5 5.5 7.3 <2.0 <2.0Calcium NS NS NS 101000 98900 99600 103000 95500 96100Copper 1,000 1,300 1,300 2.6 B <2.0 <2.0 <2.0 <2.0 <2.0Iron 300 300(c) NS 994 981 983 758 69.4 B 24.0 BMagnesium NS NS NS 1910 B 1890 B 1920 B 1930 B 3520 B 3500 BManganese 50 (g) 50(c) NS 17.1 16.5 18 16.4 2.2 B 2.3 BPotassium NS NS NS 3490 B 3140 B 3260 B 3230 B 5920 6020Sodium 160,000 (f) NS NS 17200 17300 17600 17700 15200 14900Zinc 5,000 (g) 5,000(c) NS 95.6 20.1 16.4 B 8.3 B 27.3 16.7 B

All samples analyzed by Savannah Laboratories, Tallahassee, Florida< not detected at specified detection limitBold > equal or greater than BG PAGE 3 OF 4Bold & Shaded > equal or greater than2* BGNS - no standard

Notes:(c) - EPA Secondary Drinking Water Standard(d) - EPA Primary MCL(e) - EPA Final MCLIf) - Florida Primary MCL(g) - Florida Secondary Drinking Water StandardB - Value is less than CRQL but greater than IDLW - post digestion spike for furnace AA out of control limits

TABLE 2-17SUMMARY TABLE OF DETECTED COMPOUNDS IN GROUNDWATER

OU-7, ENTOMOLOGY STORAGE AREAMONTGOMERY WATSON, 1993 INVESTIGATION

HOMESTEAD ARB, FLORIDA(CONTINUED)

Analyte

FloridaDrinking

WaterStandard

EPA DrinkingWater

Standard

EPA MaximumContaminant

Level Goal

Sample IDDate Collected

P2-DMW-00013/12/93Filtered

P2-DMW-90013/12/93Filtered

P2-EB-0001 3/3/93

P2-EB-00013/3/93

Filtered

P2-EB-00023/12/93

P2-EB-00023/12/93 Filtered

Metals (mg/l)Aluminum 200 50-200(c) NS <20.0 <20.0 <20.0 <20.0 <20.0 <20.0Arsenic 50 (f) 50 (d) NS <5.0 W <5.0 W <5.0 <5.0 <5.0 <5.0 WBarium 1,000 (f) 2,000 (d) 2,000 (g) 11.0 B 11.4b <1.0 <1.0 1.2 B <1.0Cadmium 5(f) 5 (e) 5 (e) <2.0 <2.0 <2.0 <2.0 <2.0 <2.0Calcium NS 1,000(c) NS 95800 95100 53.7B 38.7B 322B 36.0BCopper 1,000 1,300 1,300 <2.0 <2.0 <2.0 <2.0 <2.0 <2.0Iron 300 300(c) NS 11.7B <7.0 <7.0 <7.0 <7.0 47.6BMagnesium NS NS NS 3540B 3520B <30.0 <30.0 <30.0 <30.0Manganese 50 (g) 50(c) NS 2.4B 2.3B <1.0 <1.0 <1.0 <1.0Potassium NS NS NS 6010 6020 <325 <325 <325 <325Sodium 160,000

(f)NS NS 15100 15000 50.3 B <30.0 <30.0 40.2 B

Zinc 5,000 (g) 5,000(c) NS 11.7B 20.8 8.1 B 6.3 B 17.9 B 14.5B

All samples analyzed by Savannah Laboratories, Tallahassee, Florida< not detected at specified detection limitBold > equal or greater than BG PAGE 4 OF 4Bold & Shaded > equal or greater than2* BGNS - no standard

Notes:(c) - EPA Secondary Drinking Water Standard(d) - EPA Primary MCL(c) - EPA Final MCL(f) - Florida Primary MCL(g) - Florida Secondary Drinking Water StandardB - Value is less than CRQL but greater than IDLW - post digestion spike for furnace AA out of control limits

28

well below the Florida Groundwater Guidance Concentrations and Federal Drinking Water Standards(Table 2-15).

1993 Investigation. One shallow (P2-MWI) and one deep (P2-DMW-0001) monitoring well weresampled for BNAs in the 1993 investigation. Groundwater samples from both wells were collectedin duplicate. Several BNAs, mostly PAHs, were detected in the sample and duplicate collected fromP2-MWl. Total PAHs in sample P2-MW1 and duplicate P2-MW91 were 29.8 µg/1 and 26.4 µg/l.Both of these values exceed FDEP 62-770 guidelines of <10 µg/1 for total PAHs. Total PAHsdetected in sample P2-DMW-0001 and duplicate P2-DMW-9001 were 0.5 µg/1 and 3 µg/l,respectively.

Additional BNAs (non-PAHs) detected in groundwater include phenol in P2-DMW-0001 andP2-DMW-9001 at 4 µg/1 and 35 µg/l, respectively; 2-chlorophenol in P2-DMW-9001 at 3 µg/l;dibenzofuran in P2-MWl, P2-MW91 and P2-DMW-9001 at 3 µg/l, 2 µg/l and 0.7 µg/l, respectively;diethyl phthalate in P2-DMW-9001 at 0.3 µg/l; n-nitrosodiphenylamine in P2-DMW-0001 at 0.8 µg/l;di-n-butyl phthalate in P2-DMW-0001 and P2-DMW-9001 at 0.6 µg/l and 2 µg/l, respectively; andbis(2-ethylhexyl)phthalate in P2-MW1, P2-MW91, P2-DMW-0001, and P2-DMW-9001 at 1 µg/l,1 µg/l, 0.2 µg/l, and 1 µg/l, respectively. A summary of constituents detected in groundwater duringthe 1993 investigation is provided as Table 2-17.

1994 Investigation. No groundwater samples were collected for BNA analysis during the 1994 IRA.

Organochlorine Pesticide/PCBs. 1991 Investigation. In 1991, five groundwater samples, I-15,I-16, HS-16, HS-9016 (the duplicate of HS-16), and P2-MW1 were analyzed for pesticidecompounds (Table 2-6). Two pesticide compounds, 4,4'-DDD and 4,4'-DDE, were detected in onlyone groundwater sample, P2-MW1, at concentrations of 8.7 and 0.095 µg/l, respectively. No otherpesticide compounds were detected above their respective quantitation limits in the five groundwatersamples collected during this investigation. In 1991, the aerial extent of pesticide compoundsdissolved in groundwater was limited to the immediate vicinity of P2-MW1 in the southern portionof the site.

1993 Investigation. In 1993 groundwater samples from four shallow monitoring wells (I-15, I-16,SP4-MW4, and P2-MWl) and one deep monitoring well (P2-DMW-0001) were analyzed fororganochlorine pesticides and PCBs. PCBs were not detected in any of the samples collected.Groundwater samples from P2-MW1 and P2-DMW-0001 were collected

29

in duplicate. DDT and/or its metabolites were detected in four of the five wells sampled. DDT wasdetected in samples P2-MW1, duplicate P2-MW91, P2-DMW-0001, duplicate P2-DMW-9001, andSP4-MW4 at concentrations of 0.023 µg/l, 0.022 µg/l, 0.078 µg/l, 0.11 µg/l and 0.075 µg/l,respectively. The DDD metabolite was detected in samples P2-MW1, duplicate P2-MW91,P2-DMW-0001, duplicate P2-DMW-9001, SP4-MW4, and I-15 at concentrations of 10 µg/l, 9.6µg/l, 0.16 µg/l, 0.18 µg/l, 0.019 µg/l, and 0.23 µg/l, respectively. The DDE metabolite was detectedin samples P2-MW1, duplicate P2-MW91, and SP4-MW4 at concentrations of 0.12 µg/l, 0.09 µg/l,and 0.044 µg/l, respectively. Alpha-BHC was detected in sample P2-MW1 and its duplicateP2-MW91 at concentrations of 0.030 µg/1 and 0.024 µg/l, respectively. A summary of constituentsdetected in groundwater during the 1993 investigation is provided as Table 2-17.

1994 Investigation. No groundwater samples were collected for pesticide analysis during the 1994Interim Removal Action.

Metals and Cyanide. 1991 Investigations. The following metals were detected in one or more ofthe groundwater samples collected in 1991 by G&M: aluminum, barium, calcium, chromium, iron,magnesium, manganese, nickel, potassium, sodium, vanadium, lead, and arsenic. Calcium, potassium,magnesium, and vanadium were detected in the five groundwater samples analyzed for TAL metals;however, no groundwater quality standards or guidelines exist for these metals (Table 2-15).

Groundwater samples collected from HS-16, HS-9016, I-15, I-16, and P2-MW1 contained very highconcentrations of total calcium, 1,300,000, 1,700,000, 8,900,000, 2,500,000, and 370,000 µg/l,respectively. The sampling logs for all 5 samples indicate that the samples were turbid. It is probablethat the high TAL metal concentrations, particularly calcium, are a result of suspended sediments andthereby overstate the actual concentrations of the analyses at the site (G&M, 1992d). These calciumconcentrations are significantly higher than the calcium concentration range (55,000 to 140,000 µg/1)reported in the Biscayne Aquifer by Sonntag (1987).

Arsenic was detected in samples HS- 16, HS-9016, I-15, I-16, and P2-MW 1 at concentrations of34, 38, 150, 29, and 960 µg/l, respectively. The arsenic concentrations detected in I-15 (150 µg/1)and P2-MW1 (960 µg/1) exceed the Florida Primary Drinking Water Standard and Federal MCL fordrinking water of 50 µg/l for arsenic. Barium was detected in all samples collected, except P2-MW1,at concentrations ranging from 39 to 120 µg/1 which are well

30

below the Florida Primary Drinking Water Standard of 1000µg/I and the Federal MCL for drinkingwater of 2000 µg/l.

Chromium concentrations were detected above the Florida Primary Drinking Water Standard of 50µg/l and the Federal MCL for drinking water of 100 µg/l in sample I-15 at a concentration of 320µg/l. Sodium was detected in all wells sampled at concentrations ranging from 11,000 to 28,000 µg/1which were well below the Florida Primary Drinking Water Standard of 160,000 µg/l.

Lead was detected in samples HS-16, HS-9016, I-15, SP4-MW4, SP4-MW5, SP10-MW-0003,SP10-MW-0004, SP10-MW-0005 and its duplicate SP10-MW-9005, and SP10-MW-0006 atconcentrations of 21, 24, 20, 15, 11, 230, 12, 140, 160, and 240 µg/l, respectively which exceed theFederal Action Level for lead of 15 µg/1 in all samples except SP4-MW4, SP4-MW5, andSP10-MW-0004. Total lead concentrations detected in samples SP10-MW-0003, SP10-MW-0005and its duplicate SP10-MW-9005, and SP10-MW-0006 exceeded the Florida Primary Drinking WaterStandard of 50 µg/l. The aerial extent of total lead dissolved in groundwater is primarily locatedoff-site in the southeastern corner of the site in the vicinity of Site ST-18. In addition, a localized areaof total lead dissolved in the groundwater is located in the immediate vicinity of I-15. Nickel wasdetected in one sample I-15 at a concentration of 44 µg/l, which is below the Florida GroundwaterGuidance Concentration of 150 µg/l and the Federal MCL of 100 µg/l.

Federal Secondary Drinking Water Standards establish recommended limits and deal with theaesthetic qualities of drinking water; however, the FDEP has adopted these standards as the FloridaSecondary Drinking Water Standards and requires that potable groundwater shall meet theserecommended limits. Iron, which is naturally high in the Biscayne Aquifer and commonly exceeds theFlorida standard (Sonntag, 1987), was detected in all of the monitoring wells sampled for TAL metalsat concentrations ranging from 630 to 23,000 µg/1 which exceed the Federal Secondary MCL fordrinking water and the Florida Secondary Drinking Water Standard of 300 µg/l (Table 2-15). TheFederal Secondary MCL for drinking water and Florida Secondary Drinking Water Standard formanganese (50 µg/1) was exceeded in two samples, I-15 and I-16, at concentrations of 880 and 99µg/l, respectively. Aluminum was detected in all samples at concentrations ranging from 640 to21,000 µg/l. The Federal Secondary MCL for aluminum (50 to 200 µg/1) was exceeded in allsamples.

1993 Investigation. Groundwater samples from four shallow monitoring wells (I-15, I-16,SP4-MW4, and P2-MW1) and one deep monitoring well (P2-DMW-0001) were analyzed for

31

cyanide during the 1993 investigation. Groundwater samples from P2-MW1 and P2-DMW-0001were additionally analyzed for TAL metals. Groundwater samples were analyzed for total (unfiltered)and dissolved (filtered) metals due to concerns about the elevated turbidity of the groundwatersamples collected during previous sampling events. Samples analyzed for dissolved metals were fieldfiltered using an in-line, disposable (single use) 0.45 micron filter. The groundwater samples frommonitoring wells P2-MW1 and P2-DMW-0001 were collected in duplicate for cyanide and TALmetals (both filtered and unfiltered). No cyanide was detected in any of the samples collected.

Arsenic calcium, and iron exceed both the federal and state drinking water MCL in both the unfilteredand filtered sample for well P2-MW-1 and its duplicate. Calcium was the only compound thatexceeded MCLs in the deep well P2-DMW-0001 and its duplicate. Iron exceeded the state andfederal MCLs of 300 µg/l in both the filtered and unfiltered samples P2-MW-1 and P2-MW91 rangingin concentration from 758 µg/l to 994 µg/l. However, the concentrations of calcium and iron fallwithin the range of dissolved calcium in the Biscayne Aquifer as reported by Causarus (1987) andSountage (1987), respectively. Arsenic concentrations detected between the filtered and unfilteredsamples were comparable at P2-MW-1 with concentrations ranging from 510µmg/l to 632 mg/l.These concentrations exceed both the Florida Primary Drinking Water Standards and the federalPrimary MCL of 50 µg/l.

Other dissolved metals detected at trace levels include barium, cadmium, magnesium, manganese,potassium, sodium, and zinc. Copper was detected slightly above the detection level in the unfiltersample from P2-MW-1.

Groundwater metal analytical results for filtered and unfiltered samples from the 1993 Investigationare summarized in Table 2-17.

1994 Investigation. No groundwater samples were collected for metals analysis during the 1994Interim Removal Action.

Hydrocarbon Compounds. In 1991 groundwater samples were analyzed for TRPH analysis. In1991, TRPH was detected in one of the eleven samples. TRPH was detected in the sample from wellP2-MW1 at a concentration of 14 mg/l which exceeds the Section 62-770, FAC TRPH criteria of 5mg/l (Table 2-15). The aerial extent of TRPH dissolved in groundwater is limited to the vicinity ofmonitoring well P2-MW1 and corresponds to the soil/bedrock headspace data of >50 ppm and TRPHconcentrations detected in soil/bedrock samples collected from the 4 to 6 ft interval at this location.

32

1993 and 1994 Investigation. No groundwater samples were collected for TRPH analysis duringthe 1993 or 1994 Investigations.

2.6.1.5 Summary

Subsequent to the 1994 IRA, the soil/bedrock impacts at OU-7 have been characterized by samplelocations which were not excavated as a result of the IRA. Seventy-five soil/bedrock samples fromfour investigations, including the G&M 1991 OU-7 RI the 1993 Montgomery Watson OU-7 RI, the1993 Montgomery Watson OU-3 RI and the 1994 IRA delineation and confirmation samplesprovided the sources of data for site characterization.

Characterization of OU-7 indicated remnant levels of PAHs and arsenic in soil/bedrock near areas thatwere capped by buildings or parking areas. The excavations were not extended under these coveredareas because the covers act as a cap and reduce the potential for exposure to the underlyingsoil/bedrock. Furthermore, the development of this area by the Air Force Reserve provides a cap overmuch of the site. Exposure is further reduced by the limited amount of soil which prohibits manualexcavation activities. The thickness of soil at this site, as determined from soil boring logs, indicatesa relatively thin veneer of soil, less than 12 inches.

Lead was found to exceed action levels in one sample while PAHs, primarily benzo(a)pyrene, andarsenic were found in isolated pockets above action levels. Fifteen soil/bedrock samples with arsenicconcentrations above the 15 mg/kg Removal Action Level range in concentration from 16.7 to 123mg/kg. Eight of the samples containing arsenic above the Removal Action Level are located in theSouth Area, five are located in the North Area, and one sample is located southeast of the formerPCB Spill Area. A summary of the soil/bedrock metal analytical results is presented as Table 2-13.

Volatile organic compounds were not reported above Removal Action Levels in any of thenon-excavated soil/bedrock samples. Twenty-three BNAs, primarily PAHs, were detected insoil/bedrock samples. The PAH benzo(a)pyrene was reported above the 1995 FDEP Health BasedSoil Target Level of 500 µg/kg in six samples. However, only two of these samples associated withthe South Area excavation, CS34.1 (1.8 µg/kg) and CS 19.3 (4.3 µg/kg), exceeded the current BCTacceptance level for benzo(a)pyrene of 1.5 µg/kg. Two of the samples were collected from thesouthwest corner of the North Area, while the remainder of the elevated detections were from theeast side wall samples in the South Area, adjacent to

33

the asphalt covering. Total PAH concentrations in soil/bedrock samples ranged from below thedetection limit to 43,380 µg/kg. Twenty samples had reported total PAH concentration greater thanthe 1,000 µg/kg Clean Soil Criteria of FAC 62-775.400. PAHs concentrations have been observedthroughout the Homestead ARB area and have been associated with anthropogenic sources such asasphalt. The elevated PAHs are within the range of concentrations detected in urban areas and withinthe range of values reported for road dust (Menzie, et al., 1992).

One or more pesticides were reported in each of the 1994 IRA confirmation soil/bedrock samples.However, the concentration of pesticides reported were all below the specified Removal ActionLevels in the confirmation samples. One PCB, aroclor 1260, was detected in four confirmationsoil/bedrock samples, NW 15.3 (56 µg/kg), CS 15.3 (48 µg/kg), CS23.3 (62µg/kg), and CS34.1 (97µg/kg) also below the specified Removal Action Level.

The groundwater at OU-7 appears to be relatively unaffected by former operations at OU-7.Groundwater analytical results did not indicate concentrations for VOCs, BNAs, or pesticide/PCBcompounds above state or federal drinking water standards (Table 2-16 and 2-17). Groundwatercontaminants detected during previous investigations consist primarily of metals. Groundwater metalanalytical results indicate arsenic, calcium, and iron above the USEPA and State of Florida drinkingwater standards.

The arsenic concentration of 960 µg/l in the unfiltered 1991 P2-MW 1 sample is much higher thanthat in the 1993 P2-MW1 filtered sample (534 µg/1). This is likely related to the high turbidity in the1991 P2-MW1 sample relative to the 1993 P2-MWl sample, as indicated by the respective calciumconcentrations. (1991 calcium concentration: 370,000 µg/l. 1993 calcium concentration: 101,000µg/1). This suggests that the 1993 P2-MW1 sample arsenic results are more representative of thegroundwater underlying OU-7. However, the level of arsenic found in groundwater at P2-MW1 stillexceeds state and federal MCLs. In general, groundwater metals are lower in the 1993 samples ascompared to the 1991 samples. This is presumed to be due to the groundwater sampling methodologyused during the 1993 sampling event which utilized a low flow sample pump to minimize turbidityduring sampling. With the exception of arsenic, elevated calcium and iron concentrations would beexpected given the composition of the aquifer material and are consistent with the levels of theseconstituents commonly found in the Biscayne Aquifer (Causarus, 1987).

34

A summary of constituents detected in OU-7 groundwater from the 1993 investigation is providedas Table 2-17. Figure 2-11 depicts the concentrations of arsenic and pesticides in groundwater fromthe 1991 and 1993 sampling event.

2.6.2 Potential Routes of Migration

The source of wastes at OU-7 were accidental releases of diesel fuel and pesticides. Products spilledon the ground may have moved down through the soil/bedrock profile and leached to shallowgroundwater, migrated in surface runoff, or been released to the air via direct volatilization,volatilization from groundwater, or dust emission. The drainage canal to the west may not drain thearea because the concrete wall east of the canal prevents site surface runoff from entering this canal.

Elevated levels of 7 metals (aluminum, arsenic, barium, chromium, lead, silver and vanadium) weredetected in surface soil/bedrock. Elevated levels of arsenic were observed in site soil/bedrock samplesacross the site, as well as in groundwater from within the source area. The source of the arseniccontamination is likely through the use of arsenical pesticides. Other Chemicals of Concern (COCs)include one VOC (benzene), and 5 pesticides (DDT, DDE, the alpha-chlordane and gamma-chlordaneisomers, endrin ketone and heptachlor epoxide). Six metals at elevated levels were found insubsurface soil/bedrock (aluminum, antimony, arsenic, chromium, silver, and vanadium). The isomersof chlordane had penetrated to the subsurface also.

DDE is a break-down product of DDT and is somewhat more water soluble than its parentcompound. DDE has the potential to migrate further than DDT due to this characteristic.

Only metals were found as COPCs in the groundwater. There are no potable wells located on-site.In the immediate vicinity (within one mile) of the site there are two wellfields (Nos. 1 and 2). Thesewells are no longer in use. Additionally, migration to the groundwater at the two non-potable wellssouth of the site is not expected to occur because several drainage ditches and canals occur betweenthe site and these wells. Thus, there is currently little potential for exposure to affected groundwater.The base water supply is obtained currently from a wellfield located off-base and more than 1.5 milessouthwest of OU-7. Although the old on-base wells are still on-line and are used during peakconsumption periods to augment the off-site wells, this pumping is infrequent and does not alter thegroundwater on-site (Geraghty & Miller, 1992a). Future potable use of the groundwater in thevicinity of OU-7 is unlikely due to salt-water intrusion.

35

Although other contaminated media are present at OU-7, the principal route of migration ofcontaminants is through shallow groundwater. Past activities allowed contaminants to entersoil/bedrock and surface water, and the contaminants eventually migrated to shallow groundwater.

Operable Unit 7 is situated on very level topography at the Base. The cycle of water through the sitebegins with precipitation. During rainfall events, water percolates rapidly through the limestone andweathered limestone bedrock underlying the site. Surface water runoff is limited due to the flattopography and lack of drainage at OU-7. Given the highly transmissive underlying formation,rainwater typically infiltrates rapidly into the shallow aquifer system. It is estimated that horizontalgroundwater movement can be on the order of tens of feet during a single rainfall event. Once therainfall ceases, the water table returns to near static conditions and groundwater movement decreasesdramatically.

Between rainfall events, evaporation from the surface soil/bedrock returns water from the aquifer tothe atmosphere. The rate of loss is greatest with open water bodies and decreases with increasingdistance from the water table.

The natural concentrations of chemicals in the soil/bedrock, rock, and water have a controlling effecton the fate and transport mechanisms. Soil/bedrock at the site exist primarily as a veneer on thebedrock surface. The soil has both organic and iron precipitants. Nevertheless, the calcium carbonatefrom the underlying oölite is the primary mineral present.

2.7 SUMMARY OF SITE RISK

In order to evaluate whether existing or future exposure to contaminated media at OU-7 could posea risk to people or the environment, USAF completed a Baseline Risk Assessment (BRA) in May1996 with USEPA oversight of this process. This evaluation then served as a baseline for determiningwhether cleanup of each site media was necessary. In the BRA, USAF evaluated site risks forenvironmental media. This ROD addresses the risks attributable to chemicals in the soil andgroundwater at OU-7. The risk assessment included the following major components: selection ofchemicals of potential concern, exposure assessment, toxicity assessment, risk characterization,development of remedial goal options, ecological risk, and uncertainties. The USAF estimatedpotential site risk in the absence of any future remediation.

36

2.7.1 Selection of Chemicals of Potential Concern

This section presents an analysis of the site data to determine which chemicals present in site samplesare potentially responsible for the greatest risks at the site. These chemicals are designated chemicalsof potential concern (COPCs). The selection of COPCs allows the risk assessment to focus on amanageable list of the most important chemicals, which in turn permits concise analysis andpresentation of information during the remainder of the risk assessment.

2.7.1.1 Criteria For Selection. The process of selecting the COPCs involves four criteria. The firstcriterion involves determining whether a chemical is present within its range of natural backgroundconcentrations. Chemicals present at background levels are not selected as COPCs. Tables 2-12 and2-14 present soil and groundwater background data, respectively.

The second criterion is whether a chemical represents at least one percent of the risk in a given media,based on a screening method that involves the concentration and toxicity of the chemical. Factorsother than concentration and toxicity are considered to potentially modify this criterion to includeadditional chemicals that account for less than one percent of the risk. These factors include physicaland chemical properties of a given chemical, environmental persistence, medium-specific mobility,the potential to bioaccumulate, potential routes of exposure, the spatial extent of the chemical, andthe range and magnitude of concentrations detected.

Changes in COPC screening guidance have occurred. At the request of regulators, this change inguidance was incorporated into this document by screening chemicals detected in site samples usingan additional method based on USEPA Region III Risk-Based Concentrations (RBCs). Thisadditional screening is discussed further in Section 2.7.1.4.

The third criterion is whether a chemical is an essential human nutrient that is only toxic at very highdoses (i.e., at doses that are both much higher than beneficial levels and much higher than could beassociated with contact at the site). Chemicals typically considered under this criterion includecalcium, iron, magnesium, potassium, and sodium.

The fourth criterion is to determine frequency of detection in a given medium. When chemicals aredetected in less than five percent of the samples for a given medium, they are

37

not selected as chemicals of concern. However, the number of samples at OU-7 for any given mediumis no more than 24. Therefore this criterion was not used for OU-7. The following paragraphs discussthe three criteria above in greater detail.

Background levels have been estimated for groundwater, surface soil, and subsurface soil. As perRegion IV risk assessment guidance (USEPA, 1992b), inorganic chemicals where the maximumdetected concentration is less than twice the background concentration are considered to be presentat background levels. Exceptions to this rule have been made for known human carcinogens such asarsenic and chromium (assumed to present in the hexavalent state, or Cr(VI)). For these metals, themaximum detected concentration has been required to be less than background to assume that themetal is present at background levels.

The results of COPC screening for groundwater, surface soil, and subsurface soil are summarized inTables 2-18, 2-19, and 2-20, respectively.

Soil. For surface soil, five Base-wide background samples were collected by Geraghty & Miller in1991. These samples include SP11-SL-0028-2, P3-SL-0023, P2-SL-0023-2, SP3-SL-0004-1, andSP3-SL-0004-2. For subsurface soil, two background samples (SP11-SL-0028-6 and SP7-SL-0002)were collected. Soil background values are summarized in Table 2-12. As in the case of groundwater,data concerning typical chemical concentration ranges in soil are used to place the site data inperspective. In particular, data from Hem (1989) concerning carbonate sediments are employed forthis purpose.

Groundwater. For groundwater, United States Geological Survey (USGS) data on the BiscayneAquifer have been used for comparison with site groundwater samples. The USGS data aresummarized in Table 2-14. While it is generally considered preferable to determine backgroundconcentrations with wells immediately upgradient of the site, the monitoring well P2-I-15 designatedby Geraghty & Miller as a background well has concentrations of several metals which are greaterthan associated site samples, and which are also above regulatory concentrations. These resultsindicate that this well is probably not representative of background levels, and the USGS data aremore likely to represent undisturbed conditions.

Other sources of background information for groundwater include data concerning typical chemicalconcentration ranges in groundwater. These data have been used to place the site data in perspective.

TABLE 2-18

SUMMARY OF CHEMICAL OF POTENTIAL CONCERN IN GROUNDWATEROU-7,ENTOMOLOGY STORAGE AREA

Homestead Air Reserve Base, Florida(Page 1 or 2)

ConstituentMinimum

ConcentrationMaximum

Concentration

No. ofWells

With Detects

Preliminary ScreeningSummary

VOCs (µg/L)Bromodichloromethane 4 4 1/5 Included2

Chloroform 9 9 1/5 Included2

Dibromochloromethane 2 2 1/5 Included2

BNAs (µg/L) Acenaphthene 5.3 5.3 1/5 Excluded, low score1

Anthracene 2.0 2.0 1/5 Excluded, low score1

bis(2-Ethylhexyl)phthalate 1.0 1.0 2/5 Excluded, low score1

Butylbenzylphthalate 0.5 0.5 1/5 Excluded, low score1

Di-n-butylphthalate 1.0 2.0 2/5 Excluded, low score1

Dibenzofuran 0.7 5.0 3/5 Excluded, low score1

Diethylphthalate 0.3 0.3 1/5 Excluded, low score1

Fluoranthene 0.8 0.8 2/5 Excluded, low score1

Fluorene 1.0 9.9 3/5 Excluded, low score1

2-Methylnaphthalene 0.3 34.0 4/5 Excluded, low score1

N-nitrosodiphenylamine 0.8 0.8 1/5 Excluded, low score1

Naphthalene 0.6 12.0 4/5 Excluded, low score1

Phenanthrene 0.7 15.0 4/5 Excluded, low score1

Phenol 35.0 35.0 1/5 Excluded, low score1

Pyrene 0.6 1.0 2/5 Excluded, low score1

TPHs (µg/L) 51.0 882 2/2 Included2

TABLE 2-18

SUMMARY OF CHEMICALS OF POTENTIAL CONCERN IN GROUNDWATEROU-7, ENTOMOLOGY STORAGE AREA

Homestead Air Reserve Base, Florida(Page 2 of 2)

Chemical(µg/l) Minimum

ConcentrationMaximum

Concentration

No. ofWells

With DetectsPreliminary Screening

Summary

Pesticides (µg/L)Alpha-BHC 0.03 0.03 1/5 Included2

DDD 0.18 10 3/5 Included2

DDE 0.09 0.12 2/5 Excluded, low score1 DDT 0.02 0.11 2/5 Excluded, low score1

Inorganics (mg/L)Aluminum 0.049 4.3 5/5 Included2

Arsenic 0.0025 0.96 5/5 IncludedBarium 0.0056 0.039 4/5 Excluded, low score1

Cadmium 0.001 0.0055 2/5 IncludedCalcium 101 2,500 5/5 Included, qualitative, high conc essential nutrientChromium (VI) 0.026 0.026 1/5 IncludedCopper 0.0026 0.0026 1/5 Excluded, low score1

Iron 0.069 2.5 5/5 Excluded,below Biscayne Aquifer value, essential nutrientLead 0.024 0.024 1/5 Included, above current action levelMagnesium 1.91 7.7 5/5 Excluded, below Biscayne Aquifer value, essential nutrientManganese 0.0023 0.099 5/5 IncludedPotassium 1.8 6.0 4/5 Excluded, below Biscayne Aquifer value, essential nutrientSodium 11.0 17.3 5/5 Excluded, below Biscayne Aquifer value, essential nutrientVanadium 0.013 0.013 1/5 Excluded, low score1

Zinc 0.027 0.10 3/5 Excluded, low score1

Note:(1)Low score indicates <1% results for concentration-toxicity screen (USEPA,1989) for the RfD and/or SF calculation (see Table 2-6).(2)Chemical was included as a COPC based on additional screening using benchmarks based on USEPA Region III Risk-Based Concentrations (RBCs); see Section 2.6 for details.

TABLE 2-19

SUMMARY OF CHEMICALS OF POTENTIAL CONCERN IN SURFACE SOIL ATOU-7, ENTOMOLOGY STORAGE AREA

Homestead Air Reserve Base, Florida(Page 1 of 3)

Constituent MinimumConcentration

MaximumConcentration

No. of Samples

With Defects

Preliminary Screening Summary

VOCs (µg/kg)Acetone 4 560 10/14 Excluded, equipment decontamination contaminantBenzene 24 24 1/14 Included, Class A carcinogen1,l-Dichloroethene 25 25 1/14 Excluded, low score1

Chlorobenzene 19 19 1/14 Excluded, low score1

Methylene Chloride 3 720 8/14 Excluded, low score1

Toluene 1 23 3/14 Excluded, low score1

Trichloroethene 19 19 1/14 Excluded, low score1

Xylenes (total) 1 1 1/14 Excluded, low score1

BNAs (µg/kg)Acenaphthylene 57 57 1/15 Excluded, low score1

Anthracene 110 220 2/15 Excluded, low score1

Benzo(a)anthracene 65 1,400 5/15 Included2

Benzo(a)pyrene 66 970 5/15 Included2

Benzo(b)fluoranthene 69 2,000 6/15 Included2

Benzo(g,h,i)perylene 44 550 4/15 Excluded, low score1

Benzo(k)floranthene 66 500 4/15 Excluded, low score1

bis(2-Ethylhexyl)phthalate 52 130 3/15 Excluded, low score1

Butylbenzylphthalate 8.6 8.6 1/14 Excluded, low score1

Carbazole 59 92 2/13 Excluded, low score1

Chrysene 79 1,300 6/15 Excluded, low score1

Di-n-butylphthalate 56 1,010 4/15 Excluded, low score1

Di-n-octylphthalate 10 10 1/14 Excluded, low score1

Dibenzo(a,h)anthracene 17 280 3/15 Included2

Fluoranthene 97 1,900 8/15 Excluded, low score1

Indeno(1,2,3-c,d)pyrene 45 630 5/15 Excluded, low score1

2-Methylnaphthalene 43 84 2/15 Excluded, low score1

Naphthalene 50 50 1/15 Excluded, low score1

Phenanthrene 50 1,100 3/15 Excluded, low score1

Pyrene 92 2,200 6/15 Excluded, low score1

TABLE 2-19

SUMMARY OF CHEMICALS OF POTENTIAL CONCERN IN SURFACE SOIL ATOU-7, ENTOMOLOGY STORAGE AREA

Homestead Air Reserve Base, Florida(Page 2 of 3)

Constituent MinimumConcentration

MaximumConcentration

No. of Samples

With DefectsPreliminary Screening

Summary

Pesticides/PCBs (µg/kg)alpha-BHC 15 15 1/24 Excluded, low score1

delta-BHC 83 83 1/24 Excluded, low score1

Chlorodane isomers 7.6 3,500 15/25 IncludedDDD 4.8 890 15/25 Excluded, low score1

DDE 5.1 2,200 19/25 IncludedDDT 12 4,600 18/25 IncludedEndosulfan sulfate 540 541 1/25 Excluded, low score1

Endrin Ketone 1200 1,200 1/25 IncludedHeptachlor 4.6 37 3/24 Excluded, low score1

Heptachlor epoxide 6.8 94 3/24 IncludedMethoxychlor 960 960 1/25 Excluded, low score1

Inorganics (mg/kg)Aluminum 681 17,700 14/14 IncludedArsenic 0.49 44.5 30/31 IncludedBarium 5.2 451 15/15 IncludedBeryllium 0.012 1.1 6/15 Excluded, below site backgroundCadmium 1.6 1.6 1/15 Excluded, low score1

Calcium 24100 716,000 14/14 Excluded, essential nutrient (qualitative evaluation)Chromium (VI) 6.8 61.5 15/15 IncludedCopper 3.4 26.5 11/15 Excluded, low score1

Iron 484 15,500 14/14 Excluded, essential nutrient (qualitative evaluation)Lead 6.6 4.34 15/15 Excluded, below 400 mg/kg screening levelMagnesium 844 23,220 14/14 Excluded, essential nutrient (qualitative evaluation)Manganese 9.8 119 14/14 IncludedMercury 0021 0.39 5/14 Excluded, low score1

Nickel 2 2 1/15 Excluded, low score1

Potassium 330 330 1/10 Excluded, essential nutrient (qualitative evaluation)Silver 5.8 20 5/14 IncludedSodium 356 1,480 14/14 Excluded, essential nutrient (qualitative evaluation)

TABLE 2-19

SUMMARY OF CHEMICALS OF POTENTIAL CONCERN IN SURFACE SOIL ATOU-7, ENTOMOLOGY STORAGE AREA

Homestead Air Reserve Base, Florida(Page 3 of 3)

ConstituentMinimum

ConcentrationMaximum

Concentration

No. of Samples

With DefectsPreliminary Screening

Summary

Inorganics (mg/kg)Vanadium 4 26.5 4/14 IncludedZinc 5 222 15/15 Excluded, low score1

Cyanide 20 20 1/14 Excluded, low score1

Notes:(1) Low score indicates <1% result for concentration-toxicity screen (USEPA, 1989) for the RfD and/or SF calculation (see Table 2-7).(2) Chemical was included as a COPC based on additional screening using benchmarks based on USEPA Region III Risk-Based Concentration (RBCs)

See Section 2.6 for details.

TABLE 2-20

SUMMARY OF CHEMICAL OF POTENTIAL CONCERN IN SUBSURFACE SOIL (>2FT) ATOU-7, ENTOMOLOGY STORAGE AREA

Homestead Air Reserve Base, Florida(Page 1 of 3)

Constituent MinimumConcentration

MaximumConcentration

No. of Samples

With DefectsPreliminary Screening

Summary

VOCs (µg/kg)Acetone 3 1,600 21/29 Excluded, equipment decontamination contaminantBromomethane 350 350 1/29 Excluded, low score1

Methylene 2 2,100 18/29 Excluded, low score1

Tetrachloroethene 4,800 4,800 1/2 Excluded, low score1

Xylenes (total) 160 200 2/29 Excluded, low score1

BNAs (µg/kg)Ancenapthene 1,700 1,700 1/36 Excluded, low score1

Acenaphthylene 41 110 2/36 Excluded, low score1

Anthracene 45 6,300 5/36 Excluded, low score1

Benzo(a)anthracene 18 1,500 10/36 Excluded, low score1

Benzo(a)pyrene 14 1,000 11/36 Included2

Benzo(b)flouranthene 44 2,000 9/36 Excluded, low score1

Benzo(g,h,i)perylene 44 810 6/36 Excluded, low score1

Benzo(k)fluoranthene 47 510 8/36 Excluded, low score1

bis(2-Ethylhexyl)phthalate 45 944 8/35 Excluded, low score1

Butylbenzylphthalate 13 13 1/29 Excluded, low score1

Carbazole 50 310 2/27 Excluded, low score1

Chrysene 43 1,300 11/36 Excluded, low score1

Di-n-butylphthalate 47 677 12/36 Excluded, low score1

Di-n-octylphthalate 25 25 1/29 Excluded, low score1

Dibenzofuran 2,600 2,600 1/29 Excluded, low score1

Dibenzo(a,h)anthracene 60 350 41/29 Excluded, low score1

Fluoranthene 27 2,700 14/36 Excluded, low score1

Fluorene 56 3,400 2/36 Excluded, low score1

Indeno(1,2,3-cd)pyrene 64 830 6/36 Excluded, low score1

2-Methylnaphthalene 44 8,100 2/29 Excluded, low score1

Naphthalene 3,100 3,100 1/36 Excluded, low score1

Phenanthrene 46 5,800 10/36 Excluded, low score1

Pyrene 6.5 2,600 14/36 Excluded, low score1

TABLE 2-20

SUMMARY OF CHEMICAL OF POTENTIAL CONCERN IN SUBSURFACE SOIL (>2FT) ATOU-7, ENTOMOLOGY STORAGE AREA

Homestead Air Reserve Base, Florida(Page 2 of 3)

Constituent MinimumConcentration

MaximumConcentration

No. of Samples

With DefectsPreliminary Screening

Summary

Pesticides/PCBs (µg/kg)Aldrin 2.6 38 2/40 Excluded, low score1

alpha-BHC 2.6 2.6 1/40 Excluded, low score1

beta-BHC 2.6 9 4/47 Excluded, low score1

delta-BHC 2.6 12 3/40 Excluded, low score1

gamma-BHC 2.6 10 2/40 Excluded, low score1

Chlordane isomers 2.0 1,890 29/47 IncludedDDD 2.4 650 31/47 Excluded, low score1

DDE 2.1 460 30/47 Excluded, low score1

DDT 6 1,100 37/47 Excluded, low score1

Dieldrin 5.1 50 4/40 Excluded, low score1

Endosulfan I (alpha) 5.1 5.1 1/38 Excluded, low score1

Endosulfan II (beta) 8 13 2/40 Excluded, low score1

Endosulfan sulfate 6 20 2/47 Excluded, low score1

Endrin 5.1 230 5/40 Excluded, low score1

Endrin Aldehyde 2.7 18 2/28 Excluded, low score1

Endrin Ketone 5.9 23 4/47 Excluded, low score1

Heptachlor 2.6 450 13/40 Excluded, low score1

Heptachlor epoxide 3.8 13 5/40 Excluded, low score1

Methoxychlor 100 100 1/40 Excluded, low score1

Toxaphene 200 200 1/21 Excluded, low score1

Acrolor 1260 56 56 1/28 Excluded, low score1

Inorganics (mg/kg)Aluminum 199 52,800 29/29 IncludedAntimony 14.6 14.6 1/36 Include, high detection limitsArsenic 0.62 47.3 29/36 IncludedBarium 4 156 36/36 Excluded, low score1

Beryllium 0.12 2.5 13/36 Excluded, below site backgroundCalcium 48,400 726,000 29/29 Excluded, essential nutrient (qualitative evaluation)Chromium (VI) 3.1 145 35/36 Included

TABLE 2-20

SUMMARY OF CHEMICALS OF POTENTIAL CONCERN IN SUBSURFACE SOUL (>2FT) ATOU-7, ENTOMOLOGY STORAGE AREA

Homestead Air Reserve Base, Florida(Page 3 of 3)

Constituent MinimumConcentration

MaximumConcentration

No. of Samples

With DefectsPreliminary Screening

Summary

Inorganics (mg/kg) (continued)Cobalt 10 10 2/29 Excluded, low score1

Copper 0.41 25 14/36 Excluded, low score1

Iron 45 46,200 28/29 Excluded, essential nutrient (qualitative evaluation)Lead 0.79 115 29/36 Excluded, below 400 mg/kg screening levelMagnesium 513 2,880 29/29 Excluded, essential nutrient (qualitative evaluation)Mangansese 3 167 27/29 IncludedMercury 0.21 0.21 1/27 Excluded, low score1

Nickel 11 22.9 2/36 Excluded, low score1

Potassium 1,320 1,320 1/29 Excluded, essential nutrient (qualitative evaluation)Selenium 49 49 1/29 Excluded3

Silver 5.6 19.7 6/29 IncludedSodium 336 1,700 29/29 Excluded, essential nutrient (qualitative evaluation)Vanadium 4 109 3/29 IncludedZinc 0.43 129 31/36 Excluded, low score1

Notes:(1) Low score indicates <1% result of concentration-toxicity screen (USEPA, 1989) for the RfD and/or SF calculation (see Table 2-8).(2) Chemical was included as a COPC based on additional screening using benchmarks based on USEPA Region III Risk-Based Concentrations (RBCs);

see Section 2.6 for details.(3) Chemical was not included as a COPS based on additional screening using benchmarks based on USEPA Region III Risk-Based Concentrations

(RBCs) see Section 2.6 for details.

38

2.7.1.2 Concentration-Toxicity Screen. The concentration-toxicity screen is used to calculateindices that rank the chemicals according to their relative potentials to create health risks at the site.One index is used to rank chemicals according to their potential for initiating or promoting cancers,and a second index ranks chemicals according to their potential for chronic non-cancer effects. Thefirst index applies only to carcinogens, while the latter index applies to noncarcinogens. These indicesare used for ranking purposes only, and do not represent actual risk values.

The index used for ranking carcinogens involves the use of a slope factor (SF). Studies ofcarcinogenicity tend to focus on identifying the slope of the linear portion of a curve of dose versusresponse. A plausible upper-bound value of the slope is called the slope factor.

The index used to rank chemicals according to their potential to cause noncarcinogenic effectsinvolves the use of a reference dose (RfD). A chronic RfD is an estimate of a daily exposure level forwhich people, including sensitive populations, do not have an appreciable risk of suffering significantadverse health effects. Most SFs and RfDs were obtained from the Integrated Risk InformationSystem (IRIS), or, if not available there, from the Health Effects Assessment Summary Tables(HEAST).

The index for carcinogenic effects is calculated by taking the maximum detected concentration ofeach contaminant and multiplying by the oral slope factor. The inhalation SF is used for chemicals thatare only carcinogenic by inhalation (chromium and cadmium). The index for noncarcinogenic effectsis calculated by taking the maximum detected concentration of each contaminant and dividing by theoral RfD. Chemicals making up at least one percent of the total index for all chemicals have beenselected as COPCs (unless the chemical has been eliminated based on background or essential nutrientconsiderations). Concentration toxicity screening results for groundwater, surface soil, and subsurfacesoils are presented in Tables 2-21, 2-22, and 2-23, respectively. Due to changes in guidance duringthe development of this document, an additional toxicity - screening method, based on Region IIIRBCs, was also used to screen for COPCs. This method is described in Section 2.7.1.4.

2.7.1.3 Data Analysis. This subsection is organized according to media (groundwater, surface soil,and subsurface soil). Within each medium, the data are presented in the order of volatile organiccompounds (VOCs), semi volatile organic compounds (SVOC), pesticides/polychlorinated biphenyls(PCBs), inorganics. Comparisons are made to the four criteria listed in Section 2.7.1.1, and thenchemicals of potential concern are selected. The

summary Tables 2-18 through 2-20 present for each chemical, the range of concentrations, thefrequency of detection, and whether the chemical has been selected as a chemical of potentialconcern.

The analytical data for this risk assessment were collected by Geraghty & Miller during investigationsin 1989 and 1991, Montgomery Watson during 1993 and IT Corporation in 1994. An in-depthdiscussion of the sample collection and analytical methodology is presented in Section 2.0 of theMontgomery Watson RI (1996). These analytical data were reduced and analyzed for use in the riskassessment according to guidelines provided by USEPA (1989a, 1991). Geraghty & Miller and ITCorporation performed laboratory analyses and data validation for their field samples; MontgomeryWatson performed its own data validation, which is reported in a Quality Control Summary Report,while Savannah Laboratories performed the laboratory analyses. All data collected by Geraghty &Miller in 1991, Montgomery Watson in 1993, and IT Corporation in 1994 were reviewed for this riskevaluation. This includes a review of detects, detection limits for non-detects, and estimated(J-qualified) data. Detection limits reported for Montgomery Watson samples were in compliancewith Contract Laboratory Protocol Scope of Work (CLP SOW) contract required quantitation limits(CRQL).

Sample quantitation limits (SQL) at levels suitably low for risk assessment use were not consistentlyachieved. In the subsurface soil data base obtained in 1994 by IT Corp, three of 27 samples hadSVOC SQL at 8000 to 8100 Mg/kg while all others were 2000 Mg/kg and below. In 1989, thethallium detection limit in all seven samples collected was 8 Mg/kg while all others were 1.0 Mg/kgand below. In both cases, had maximum concentrations at these detection limit levels been used inthe toxicity screen, it could have affected the outcome of the selection of COPCs. The majority ofthe data obtained during other sampling events had acceptable detection limits for thallium andSVOCs which indicated that these chemicals were of limited occurrence on site. When thallium wasrepeatedly not detected in soils where a suitably low detection limit was reached, it was assumed thatthallium. was also not detected to low levels in the samples with high detection limits. Similarly, itis highly unlikely that SVOCs would have been consistently found at levels just beneath the SampleQuantitation Limit (SQL) in the samples where a high SQL was obtained. Professional judgmentindicated that inclusion of the nondetect data through use of 1/2 of the detection limit was sufficientlyrepresentative.

In reviewing the IT laboratory reports to obtain detection limits, some omissions from the SummaryTable (IT Corp, 1994) were noted. In particular heptachlor, heptachlor epoxide,

39

40

and DDE had been detected in sample point FCSN2.4 but had been omitted from the Summary Table.These chemicals were added to the MW data base so it no longer is identical to the IT SummaryTables.

Geraghty & Miller specify in their remedial investigation that groundwater was analyzed for totalpetroleum hydrocarbons (TPH), while soil was analyzed for hydrocarbons limited in size tocompounds with a carbon chain length of 8-20. Although these are two distinct analyses, both aretermed TPH for the purposes of this document.

2.7.1.4 Screening Using Risk-Based Concentrations. Guidance on COPC selection changedduring the development of this document. Therefore, an RBC-based benchmark screening methodwas added after input from regulators. Note that the use of both the toxicity-concentration screeningmethod described in Section 2.7.1.2 and the RBC method described below results in a greater numberof COPCs than use of each method singly. Therefore, selection of COPCs in this document is moreconservative.

Risk-Based Concentrations. Current USEPA Region IV guidance recommends using the RegionIII RBCs as guidance for screening. RBCs are published periodically by USEPA Region III to act asguidance in risk management, risk assessment, and remediation decisions. RBCs are generated usingdefault exposure parameters for chemicals in a specific media. Concentrations quoted in the USEPARegion III RBC Table represent risk levels of 1 x 10-6 (for carcinogens) or a hazard quotient of 1 (fornon-carcinogens). USEPA Region IV suggests that screening values for non-carcinogenic chemicalsbe adjusted to represent a hazard quotient of 0.1.

Maximum concentration values of all chemicals detected in a particular environmental medium arecompared to the appropriate RBC-based benchmark in Tables 2-24 to 2-26. Chemicals whosemaximum concentration exceeded the benchmark value were added as COPCs. The results of thisprocess are summarized below.

Groundwater. Chemicals detected in groundwater were compared to the Tap Water RBCs. Theresults of this comparison are shown in Table 2-24. The comparison resulted inbromodichloromethane, dibromochloromethane and chloroform, the pesticides alpha-BHC and DDD,TPHs, and manganese being added to the list of COPCs for groundwater. All other chemicals thatexceeded the RBC-based benchmarks had already been selected as COPCs, based on previousscreening described in Sections 2.7.1.2, 2.7.1.3, and Table 2-2 1.

41

Surface soil. Chemicals detected in surface soil were compared to RBCs for residential soil. Theresults of this comparison are shown in Table 2-25. The comparison resulted in benzo(a)anthracene,benzo(a)pyrene, benzo(b)fluoranthene, dibenzo(a,h)anthracene, and manganese being added to thelist of COPCs for surface soils. Although the maximum concentration of beryllium in surface soilexceeded its respective RBC-based benchmark, the concentrations detected were within backgroundlevels, and so beryllium was not considered a COPC in surface soil. All other chemicals detected insurface soil whose maximum concentration exceeded the RBC-based benchmarks had already beenselected as COPCs based on previous screening described in Sections 2.7.1.2, 2.7.1.3 and Table 2-22.

Subsurface Soil. Chemicals detected in subsurface soil were compared to RBCs for soil in anindustrial area. The results of this comparison are shown in Table 2-26. The comparison resulted inbenzo(a)pyrene being added to the list of COPCs for subsurface soils. Although the maximumconcentrations of beryllium in subsurface soil exceeded its respective RBC-based benchmark, theconcentrations detected were within background levels, and so beryllium was not considered a COPCin subsurface soil. In the toxicity-screening (Table 2-23), selenium contributed greater than 1% of theoverall risk for subsurface soils. However, selenium was detected in only 1 of 29 subsurface soilsamples at 49 mg/kg, and this concentration is well below both the industrial and residential RBCconcentrations. Therefore, selenium was not retained as a COPC. All other chemicals detected insubsurface soil whose maximum concentration exceeded the RBC-based benchmarks had alreadybeen selected as COPCs based on previous screening described in Sections 2.7.1.2, 2.7.1.3, and Table2-23.

2.7.1.5 Chemicals of Potential Concern Selection Process. The chemicals of potential concernselection process determines those chemicals which are the most toxic and which are anticipated tocreate the greatest potential risk.

Identification of the COPCs for the risk assessment was accomplished in accordance with USEPA(1989a) guidance. All detected chemicals were included as COPCs for the risk assessment with thefollowing exceptions:

• Chemicals that are essential human nutrients and chemicals that are toxic only at very highdoses (i.e., much higher than those that could be associated with contact at the site) wereeliminated from the quantitative risk assessment. Examples of such chemicals are calcium,magnesium, potassium, and sodium.

42

• As per USEPA Region IV risk assessment guidance (USEPA, 1992b), inorganic chemicalspresent at concentrations less than twice background concentrations were excluded from thelist of COPCs. Only those chemicals for which the maximum detected concentration wasgreater than twice the background concentration were retained as COPCs.

• Inorganic and semi-volatile organics considered to be present in background concentrationsaccording to the scientific literature for the specific chemical or those chemicals consideredubiquitous and determined not to be site-related. Although, phthalate esters, such asbis(2-ethylhexyl)phthalate and butylbenzylphthalate, are relatively ubiquitous in theenvironment, the presence of these constituents in media at the site may be due to samplingor laboratory artifacts, as well. Since these phthalates may not be site-related, for purposesof this risk assessment only the significant phthalates were considered COPCs.

• Chemicals detected in less than 5% of the samples analyzed per media (except in groundwaterwhere data was obtained from only five sample points).

• Chemicals represented in less than 1% of the potential overall risk via theconcentration-toxicity screen (USEPA, 1989), and whose maximum concentration detecteddid not exceed a benchmark based on USEPA Region III RBCs (USEPA, 1995a).

Based on the above evaluation, a group of COPCs was carried through the quantitative riskassessment for each of the environmental media, groundwater and soil. This selection is summarizedin Table 2-27.

Tentatively Identified Compounds (TICs) and TRPH. Where it was appropriate, TICs wereincluded within the quantitative risk analysis as COPCs for soil and groundwater. Tentativelyidentified chemicals in the Montgomery Watson 1993 groundwater dataset associated with petroleumproducts were summed for quantification. Categories of TICs included in this evaluation include:alkanes, unknown hydrocarbons, substituted benzenes, PAHs, cycloalkanes, and aromatics. Thesummed petroleum-related TICs were treated as TPH in screening and the risk characterization.

Unknown and other partially identified TICs were not included for further analysis due to the lackof information on these chemicals. Organic acids detected in soil and groundwater were

TABLE 2-27

CHEMICALS OF POTENTIAL CONCERNIN ENVIRONMENTAL MEDIA AT

OU-7, ENTOMOLOGY STORAGE AREAHomestead Air Reserve Base, Florida

Compound GroundwaterSurface

SoilSubsurface

Soil

VOCsBenzene XBromodichloromethane XChloroform XDibromochloromethane X

BNAsBenzo(a)anthracene XBenzo(a)pyrene X XBenzo(b)fluoranthene XDibenzo(a,h)anthracene X

TPHs X

Pesticide/PCBsAlpha-BHC XChlordane isomers X XDDD XDDE XDDT XEndrin ketone XHeptachlor epoxide X

MetalsAluminum X X XAntimony XArsenic X X XBarium XCadmium XChromium X X XLead XManganese X X XSilver X XVanadium X X

BNAs Base-neutral and acid extractable compoundsPCBs Polychlorinated biphenylsVOCs Volatile organic compounds.

43

not included in the quantitative risk assessment as these chemicals are the result of natural processesby biological organisms (bacteria) in the breaking down or “weathering” of petroleum product at thesite.

USEPA Region IV has adopted an approach to TPH developed by the State of Massachusetts DEP(Massachusetts DEP, 1994). This approach uses the toxicity values of certain hydrocarboncompounds (e.g. n-hexane, n-nonane, eicosane) for fractions of TPH. The toxicity of hydrocarbonstends to decrease with increasing carbon chain length. n-Hexane has an RfD of 0.06, n-nonane an RfDof 0.6, and eicosane an RfD of 6.

After review and discussion with USEPA Region IV, toxicity values for n-nonane (C9) were usedas surrogate values for TPH and fuel-associated TICs. Use of n-nonane as a surrogate was felt to bemore representative of the TPH present at the site than use of n-hexane, as volatile fractions of TPH(C4-C7) would be expected to attenuate by weathering more rapidly than heavier components.

2.7.2 Potential Routes of Migration

The source of wastes at OU-7 were accidental releases of diesel fuel and pesticides. Products spilledon the ground may have moved down through the soil/bedrock profile and leached to shallowgroundwater, migrated in surface runoff, or been released to the air via direct volatilization,volatilization from groundwater, or dust emission. The drainage canal to the west may not drain thearea because the concrete wall east of the canal prevents site surface runoff from entering this canal.

Elevated levels of 7 metals (aluminum, arsenic, barium, chromium, lead, silver, and vanadium) weredetected in surface soil/bedrock. Elevated levels of arsenic were observed in site soil/bedrock samplesacross the site, as well as in groundwater from within the souce area. The source of the arseniccontamination is likely through the use of arsenical pesticides. Other Chemicals of Concern (COCs)include one VOC (benzene), and 5 pesticides (DDT, DDE, the alpha-chlordane and gamma-chlordaneisomers, endrin ketone and heptachlor epoxide). Six metals at elevated levels were found insubsurface soil/bedrock (aluminum, antimony, arsenic, chromium, silver, and vanadium). The isomersof chlordane had penetrated to the subsurface also.

DDE is a break-down product of DDT and is somewhat more water soluble than its parentcompound. DDE has the potential to migrate further than DDT due to this characteristic.

44

Only metals were found as COPCs in the groundwater. There are no potable wells located on-site.In the immediate vicinity (within one mile) of the site there are two wellfields (Nos. 1 and 2). Thesewells are no longer in use. Additionally, migration to the groundwater at the two non-potable wellssouth of the site is not expected to occur because several drainage ditches and canals occur betweenthe site and these wells. Thus, there is currently little potential for exposure to affected groundwater.The base water supply is obtained currently from a wellfield located off-base and more than 1.5 milessouthwest of OU-7. Although the old on-base wells are still on-line and are used during peakconsumption periods to augment the off-site wells, this pumping is infrequent and does not alter thegroundwater on-site (Geraghty & Miller, 1992a). Future potable use of the groundwater in thevicinity of OU-7 is unlikely due to salt-water intrusion.

Although other contaminated media are present at OU-7, the principal route of migration ofcontaminants is through shallow groundwater. Past activities allowed contaminants to entersoil/bedrock and surface water, and the contaminants eventually migrated to shallow groundwater.

Operable Unit 7 is situated on very level topography at the Base. The cycle of water through the sitebegins with precipitation. During rainfall events, water percolates rapidly through the limestone andweathered limestone bedrock underlying the site. Surface water runoff is limited due to the flattopography and lack of drainage at OU-7. Given the highly transmissive underlying formation,rainwater typically infiltrates rapidly into the shallow aquifer system. It is estimated that horizontalgroundwater movement can be on the order of tens of feet during a single rainfall event. Once therainfall ceases, the water table returns to near static conditions and groundwater movement decreasesdramatically.

Between rainfall events, evaporation from the surface soil/bedrock returns water from the aquifer tothe atmosphere. The rate of loss is greatest with open water bodies and decreases with increasingdistance from the water table.

The natural concentrations of chemicals in the soil/bedrock, rock, and water have a controlling effecton the fate and transport mechanisms. Soil/bedrock at the site exist primarily as a veneer on thebedrock surface. The soil has both organic and iron precipitants. Nevertheless, the calcium carbonatefrom the underlying oölite is the primary mineral present.

45

2.7.3 Exposure Assessment

This section of the risk assessment identifies and describes potential human receptors, reviewspossible pathways of exposure for chemicals of potential concern at OU-7, and presents estimates ofexposure doses resulting from identified pathways at OU-7. An exposure assessment is conductedto identify potential sources and mechanisms of release, transport pathways (e.g. groundwater,surface water, soil, and air), routes of exposures (ingestion, inhalation, dermal contact), and potentialon-site and off-site receptor populations (current users of the site, as well as adjacent populationswhich may be exposed to chemicals that have been transported off-site). This information providesthe basis for constructing site-specific exposure scenarios.

Other information considered in the development of present and future exposure scenarios includes:physical characteristics of the site and surrounding area such as climatology, groundwater hydrology,location and description of surface water and surrounding land use and available state-specificguidelines relevant to exposure and risk assessments.

A critical step in assessing the potential risk to public health is to identify the pathways through whichexposure could occur. A typical transport pathway consists of four necessary elements: 1) a sourceand mechanism of chemical release, 2) an environmental transport medium, 3) a point of potentialcontact with the contaminated medium, and 4) an exposure route (inhalation of vapors, ingestion ofgroundwater, etc.). All four of these elements must be present for a pathway to be complete.

Three environmental media were considered in this document - groundwater, surface soil, andsubsurface soil. Guidance on what depth range should be used for surface soil differs between theUSEPA (0 to 12 inches) and the Florida DEP (0 to 24 inches). Samples taken between 0 and 24inches below level surface (bls) were considered surface soil samples, so receptor exposure duringgardening or landscaping activities could be evaluated in this assessment. This choice seemsreasonable for south Florida, as the year-round, mild climate would permit possible residentialgardening and frequent landscaping activities on base.

Exposure Point Concentration. In accordance with USEPA methodology (1989a and 1992e), themedium-specific 95 percent UCL of the arithmetic mean concentrations for the COPCs will be usedas exposure point concentrations (EPCs) to estimate reasonable maximum exposure (RME). TheRME approach is suggested by the USEPA (1989a) to provide an estimate of the maximum exposure(and therefore risk) that might occur. The

46

natural log of the data was used since environmental data is typically log normally distributed. TheRME corresponds to a duration and frequency of exposure greater than is expected to occur on anaverage basis. In those instances where the calculated 95 percent UCL exceeds the maximumdetected concentration, the maximum detected concentration was used as the EPC for a moreaccurate estimate of RME concentration (USEPA, 1989a).

The following decision criteria were used in the development of the database used to calculateexposure point concentrations.

• All chemicals that were never detected in a medium (e.g., groundwater, soil, surfacewater, sediment) were eliminated from further analysis for that group.

• All analytical results reported as detects were used at the reported value. Thisincluded estimated data (J-qualified), as well as unqualified data.

• For non-detects, one-half the practical quantitation limit (PQL) was used as a proxyconcentration (rather than using zero or eliminating the data point). In instanceswhere one-half the PQL exceeded the maximum detected concentration for thatconstituent in that data group (i.e., an unusually high PQL), the maximum detect wasused as the proxy value for that non-detect.

• For duplicate samples, the result for each chemical was selected as follows: if bothwere detects, the higher measured analytical concentration was used; if only one resultwas a positive detect, that concentration was used; if both were non-detects, one-halfthe lower PQL was used as the proxy concentration. For the case of two non-detects,the smaller PQL was used because higher PQLs are frequently the result of dilutionof the sample, and use of the higher PQL would introduce more uncertainty into thecalculation. Additionally, it is not reasonable to use the higher PQL when theduplicate analysis on the same sample has indicated that the chemical was not presentat the lower PQL.

The results of these analyses for the sampled media are presented in Tables 2-28 through 2-30. Theinformation presented in these tables includes, for each chemical of potential concern, the number ofsamples collected and included in the database developed by G&M (1989, 1991) for a preliminaryBRA and, for soils, the number of these samples which remained following the 1994 IT Corporationsoil removal activity. Similar information is presented for samples collected by Montgomery Watsonin 1993 and IT Corporation in 1994.

TABLE 2.28

EXPOSURE POINT CONCENTRATIONS FOR GROUNDWATEROU-7, ENTOMOLOGY STORAGE AREA

Homestead Air Reserve Dam, Florida

Geraghty & MillerSamples Collected

1991

Montgomery WatsonSamples Collected

1993total Number

Samples Averaged G&M MW Value Used inConstituent No. Samples

Collected & Avg.No. Samples

Collected1991-93 UCL Max Max Risk Calculation 1

VOCs (µg/l)

Bromodichloromethane 3 2 5 5.0 ND 4 4Chloroform 3 2 5 11.1 ND 9 9Dibromochloromethane 3 2 5 4.5 ND 2 2

TPHs (µg/l) NA 2 2 NC NA 882 882

PESTICIDES (µg/l)Alpha BHC 3 2 5 0.154 ND 0.03 0.03DDD 3 2 5 7.24E+13 8.7 10 10

METALs (mg/L)Aluminum 3 2 5 51,019 4.3 0.126 4.3Arsenic 3 2 5 973,871 0.96 0.54 0.96Cadmium 3 2 5 0.020 ND 0.0055 0.0055Chromium VI 3 2 5 1.96 0.026 ND 0.26Lead 3 2 5 0.16 0.024 ND 0.024Manganese 3 2 5 7.19 0.099 0.017 0.017

µg/L micrograms per Litermg/L miligram per Liter - - Not RecalculatedND Not DetectedNA Not Applicable

NC Not Calculated1

UCLs are used as exposure point concentrations unless calculation produces a UCL greater than the maximum detected concentration,in which case the maximum detected concentration is used. The UCL value is for the combined sample sets.

TABLE 2-29

EXPOSURE POINT CONCENTRATIONS IN SURFACE SOIL SAMPLESOU-7, ENTOMOLOGY STORAGE AREA

Homestead Air Reserve Base, Florida

Chemical

Geraghty & Miller 1 Montgomery Watson1 IT CorpTotalNo.

Samples6

UCLConcentration7

MaximumDetected

Concentration

Value Usedin Risk

Calculationsa

SamplesCollected

19891

SamplesRemaining

SamplesCollected

19913

SamplesRemaining

1995

SamplesCollected

19934

SamplesRemaining

1995

SamplesRemaining

19949

VOCs (µg/kg)Benzene 0 0 3 1 2 0 13 14 58,738 24 24

BNAs (µg/kg)Benzo(a)anthracene 1 0 1 2 2 0 13 15 1,663 1,400 1,400

Benzo(a)pyrene 1 0 1 2 2 0 13 15 1,505 970 970

Benzo(b)fluo ranthene 1 0 1 2 2 0 13 15 1,362 2,000 1,362

Dibenzo(a,h)anthracene 1 0 1 2 2 0 13 15 2,094 280 280

Pesticides (µg/kg)Chlordane Isomers 12 1 15 10 4 1 13 25 1,143 3,500 1,143

DDE 12 1 15 10 4 1 13 25 762 2,200 762

DDT 12 1 15 10 4 1 13 25 1,541 4,600 1,541

Endrin Ketone 0 1 15 10 4 1 13 25 56.1 1,200 56

Heptachlor Epoxide 0 0 15 10 4 1 13 24 7.7 94 7.7

Metals (mg/kg)Aluminum 0 0 3 1 2 0 13 14 7,501 17,700 7,501

Arsenic 12 1 3 1 2 0 29 31 18.0 45 18

Barium 12 1 3 1 2 0 13 15 65.2 451 65.2

Chromium VI 12 1 3 1 2 0 13 15 26.7 62 26.7

Manganese 0 0 3 1 2 0 13 14 90.9 119 90.9

Silver 0 0 3 1 2 0 13 14 10.4 20 10.4

Vanadium 0 0 3 1 2 0 13 14 11.8 26.5 11.8

µg/kgmg/kg

- -

Micrograms per kilogram Miligram per kilogram Not Recalculated

Shaded Cellls indicate the number of samples remaining from original sampling event (in column to the left) after IT Corporation excavation and sampling in 1994/1995.

12345

678

When a location was sampled in duplicate, the data is combined for risk assessment and is reported as one sample collected Geraghty & Miller, 1989 Data Points; P2SB-3 SGeraghty & Miller, 1991 Data Points: P2-SL-0016-2, P2-SL-0019-2, P2-SL-0020-2, P2-SL-0021-2, P2-SL-0023-2, P2-SL-0026-2, P2-SL-0027-2, P2-SL-0029-2, P2-SL-0029-4, P2-SL-0030-2Montgomery Watson 1993 Data Points: P2-SL-0032IT Corporation 1994 Data Points: ESA 302/3, ESA 302/4, ESA 302/5, ESA 302/6, ESA 302/7, ESA 302/8, ESA 302/9, ESA 302/10,ESA 302/11, ESA 30/12, ESA 302/13, ESA 302/14, ESA 302/16, ESA 302/17, ESA 302/18, ESA 302/22E5.1, N5.1, SW10.1, FCN2.4, CSNA.l, CSNB.1,CSE.18, CSSB.1, SB1.18, CS25.1, CS28.1, CS29.1 CS30.1Total number of samples used in the risk assessment database; the sum of the shaded cells in each row.The UCL concentration was calculated assuming a lognormal distribution of the data.The UCL concentration is used as the exposure point concentration unless it is greater than the maximum detected concentration, in which case the maximum detected concentration is used.

TABLE 2-30

EXPOSURE POINT CONCENTRATIONS IN SUBSURFACE SOIL SAMPLESOU-7, ENTOMOLOGY STORAGE AREA

Homestead Air Reserve Base, Florida

Constituent

Geraghty & Miller 1 Montgomery Watson1 IT Corp TotalUCL

Concentration 7MaximumDetected

Concentration

Value Used inRisk

Calculations 8

samplesCollected

1998 3

SamplesRemaining

1995

SamplesCollected

1991 4

SamplesRemaining

1995

SamplesCollected

1993

SamplesRemaining

1995 5

SamplesRemaining

1994 5

No.Samples 2

BNAs(µg/kg)Benzo(a)pyrene 12 7 3 2 0 0 27 36 1,038 1,000 1,000

Pesticides (µg/kg)Chlordane Isomers 12 7 15 12 2 1 27 47 550 1,890 550

Metals (mg/kg)Aluminum 0 0 3 2 0 0 27 29 3,328 52,800 3,328

Antimony 12 7 3 2 0 0 27 36 49 14.6 14.6

Arsenic 12 7 3 2 0 0 27 36 20.7 47.3 20.7

Chromium VI 12 7 3 2 0 0 27 36 13.6 145 13.6

Manganese 57 167 57.2

Silver 0 0 3 2 0 0 27 29 5.6 19.7 5.6

Vanadium 0 0 3 2 0 0 27 29 11 109 11.0

(µg/kg) Micrograms per kilogram

mg/kg Miligram per kilogram

- - Not Recalculated

Shaded cells indicate the number of samples remaining from orignal sampling event (in column to the left) after IT Corporation excavation and sampling in 1994/995.

1 When a location was sampled in duplicate, the data is combinedd for risk asessment and is reported as one sample collected.

2 Total number of samples used in the risk assessmemt database; the sum of the shaded cells in ceach row. Count includes P2 SL-0028 and P2-SL-0033 for pesticides only.However, removal status unknown and data is not incorporated within the database.

3 G&M, 1989. Data points: P2 SB-3 D, P2 SB-4 D, P2 SB-5 D, P2 SB-6 D, P2 SB-7 D, P2 SB-10 D, P2 SB-11 D

4 G&M 1991 Data Points: P2 SL-0016-4, P2 SL-0019-4, P2 SL-0020-4, P2 SL-0021-4, P2 SL-0022-4, P2 SL-0023-4, P2 SL-0024-4,P2 SL-0025-4, P2 SL-0026-4, P2 SL-0027-4, P2 SL-0029-4, P2 SL-0030-4.

5 MW 1993 Data Point: P2 SL-0032

6 ITCorp 1994 Data Points: NE.3, SW5.3, SE5.3, NW5.3, FCSN3.4, FCSN4.4, FCN1.6, NW15.1, NW15.3, CSNA.3, CSNB.3, CSSB .3,SB3.18, CS27.3, CS24.3, CS25.3, CS15.3, CS28.3, CS29.3, CS30.3, FC56.3, FCS5.3,FCS3.3, FCS2.3, FCS1.3, FCS4.5, FCS7.5

7 The UCL concentration was calculated assuming a lognormal distribution of the data

8 The UCL concentration is used as the exposure point concentration unless it is greater than the maximum detected concentration, in which case the maximum detected concentration is used.

47

Lastly the arithmetic mean, the maximum concentration detected, and the 95 percent upperconfidence limit (UCL) on the mean (one tailed test, assuming log normal distribution) is presented.The information presented in these tables is discussed in the following subsections. An example ofthe data reduction used to calculate the mean and UCL for the chemicals detected is shown in Table2-31.

Exposure Scenarios. Exposure pathways identified at OU-7 are shown in Table 2-32 and areassociated with soils and groundwater. Most of the chemicals detected at the site have lowenvironmental mobility.

Exposure points that can be identified for current or future use of the site include the groundwaterand soils at OU-7. Metals which were found as COPCs in the groundwater include aluminum, arsenic,cadmium, chromium, lead, and manganese. The pesticides alpha-BHC and DDD, and the VOCsbromodichloromethane, dichlorobromomethane and chloroform were also identified as COPCs ingroundwater. There are no potable wells located on-site. In the immediate vicinity (within one mile)of the site there are two wellfields (Nos. 1 and 2). These wells are no longer in use. Additionally,migration to the groundwater at the two non-potable wells south of the site is not expected to occurbecause several drainage ditches and canals occur between the site and these wells. Thus, there iscurrently little potential for exposure to affected groundwater.

The site is covered with crushed limestone, weathered limestone, gravel, and sparse vegetation. Nobase workers have job duties that require them to work at OU-7 for 8 hours per day, 5 days perweek. For purposes of this assessment, it was assumed that a base worker could be at the site as longas 2 hours per day, 5 days per week to store or retrieve materials. As a conservative assumption, allthree routes of exposure to soil were considered: incidental ingestion of soil, dermal (skin) contactwith soil, and inhalation of particulates and vapors. The amount of dust, vapors, and soil contact isnot likely to be significantly restricted by the gravel and sparse vegetative cover, so potential exposurerates were not reduced by a vegetation factor.

The OU-7 area has been retained by the 482nd Air Force Reserve as part of the cantonment area. Assuch, this area has been rebuilt as part of the Base Supply, Civil Engineering, and POL Operationsarea. Operable Unit 7 now includes a new civil engineering complex building, three shops, a storagearea, miscellaneous building and a much expanded parking area. Buildings or asphalt paved areas nowcover OU-7 and thus eliminate any potential exposures, direct or indirect via soil contact for futuresite workers. However, this future land

x

TABLE 2-31

EXAMPLE DATA REDUCTION CALCULATIONFOR ARSENIC IN GROUNDWATER SAMPLES AT

OU-7, ENTOMOLOGY STORAGE AREAHomestead Air Reserve Base, Florida

SampleDesignation

AnalyticalResult(µg/l)

ValueUsed(µg/l)

LogTransformedData

P2-HS-16 38 38 3.64

P2-I-a6 29J 29 3.37

P2-MW-1 (<91) 960 960 6.87

P2-MW-1 (<93 540 540 6.29

P2-DMW-0001 2.50 2.50 0.92

x s sHn

+ + −=

05 2

1.

UCL e

where:

Arithmetic mean of transformed dataTotal number of samplesDegrees of freedomStandard DeviationH-statistic of transformed data (% =0.05)Upper Confidence Limit (in mg/L)

= 4.22n = 5n - 1 = 4s = 2.41H = 11.259UCL = 9.7E+08

• All statistics were calculated using one-half the detection limit for non-detects, where applicable.

TABLE 2-32

POTENTIAL PATHWAYS OF EXPOSURE TO CHEMICALSDETECTED AT OU-7, ENTOMOLOGY STORAGE AREA

Homestead Air Reserve Base, Florida(Page 1 of 2)

Medium Pathway/RoutePotentially-Exposed

Population Comments

Groundwater (potable use) Ingestion, dermal contact, andinhalation of constituents ingroundwater.

None currently identified.Hypothetical future on-siteresidents unlikely due to natureand history of Site.

No potable wells are locatedbetween Site SS-7 and thegroundwater discharge point(drainage ditches or BoundaryCanal). No active potable wellsare located within a 1-mileradius of the site. Futurepotable use of groundwater isunlikely due to high totaldissolved solids associated withsalt-water intrusion. However,for purposes of this riskassessment, ingestion ofgroundwater by a hypotheticalfuture on-site resident wasquantitatively evaluated.

TABLE 2-32

POTENTIAL PATHWAYS OF EXPOSURE TO CHEMICALSDETECTED AT OU-7, ENTOMOLOGY STORAGE AREA

Homestead Air Reserve Base, Florida(Page 2 of 2)

Medium Pathway/RoutePotentially-Exposed

Population Comments

Soil (Weathered Bedrock) Incidental ingestion of anddermal contact with affectedsurface soils/dust and inhalationof affected dust.

Current base workers accessingthe area to drop off or retrievepiping. Hypothetical futureresidents (children and adults)on-site unlikely.

Most of the sit e is covered withsparse grass or gravel, so contactwith soil, dust, or volatilizedconstituents is possible. The siteis located approximately one-half mile south of base housingand is used currently by basepersonnel; the potential forfuture development of the site islimited due to the surroundingland use and deed restrictions.

Soil (Subsurface) Incidental ingestion of anddermal contact with affectedsurface soils/dust and inhalationof affected dust.

Future construction workerexcavating site.

Construction worker is exposedto subsurface soil contaminantsduring excavating.

48

re-use would require construction and thus potential exposure for the construction worker. Exposurepathways for potential future construction workers include incidental ingestion of dirt and inhalationof fugitive dust.

The future construction worker could be exposed to both surface and subsurface soils via ingestionand inhalation of particulates. Inhalation of vapors and dermal exposure are not quantified becausea relatively low contribution to overall site risk is expected given the nonvolatile character of OU-7COPCs. This scenario, of 1-year duration, used subchronic oral and inhalation RfDs, when they wereavailable. Hexavalent chromium had a subchronic oral RfD (2.OE-02 mg/kg/day) and barium had asubchronic inhalation RfD (1.0E-03 mg/kg/day) which differed from the chronic values.

In the unforeseen event that the site is closed, the possibilities for future exposures could include thedevelopment of the land for residential use. Exposure pathways for these hypothetical future residentshave been evaluated but are not deemed approximate for evaluating site risk. Future residentialscenarios evaluated include direct contact with the soils, incidental ingestion of the soils, andinhalation of fugitive dust or vapors.

There are no potable wells on the base between OU-7 and the groundwater discharge point at thedrainage ditches or Boundary Canal. There are no active potable wells within a 1-mile radius of thesite. The base water supply is obtained currently from a wellfield located off-base and more than 1.5miles southwest of OU-7. Although the old on-base wells are still on-line and are used during peakconsumption periods to augment the off-site wells, this pumping is infrequent and does not alter thegroundwater on-site (Geraghty & Miller, 1992a). Future potable use of the groundwater in thevicinity of OU-7 is unlikely due to saltwater intrusion. On-base wells that were used previously tosupply potable water have been replaced by the off-base wellfield due to the effects of salt-waterintrusion. Therefore, it is unlikely that new wells would be located in the area.

Although it is unlikely that potable wells would be installed in the vicinity of the site, a conservativeassumption made in this risk assessment is that a potable well is installed in the groundwater plume,downgradient of the site. Exposure of hypothetical future residents to affected groundwater viaingestion, inhalation, and dermal contact is considered a potential exposure pathway.

In summary, workers accessing the site to store or retrieve materials are the most likely populationpotentially exposed to the on-site surficial soils. The future plans for this site

49

include a new civil engineering complex building, three shops, a storage area, miscellaneous buildingand a much expanded parking area. This plan for future paving and building structures would coverall existing soils and thus eliminate any potential exposures for future site workers. However,foreseeable future land use would include construction. Therefore, the potential construction workerexposure pathway was included in this risk analysis. In the unforeseen event that the site is closed,hypothetical future exposure pathways might include residential development of the site in whichresidents are potentially exposed. Table 2-32 summarizes the potential exposure pathways for OU-7.

2.7.4 Toxicity Assessment

This section of the risk assessment provides information on the human health effects of site specificcontaminants of potential concern. The information presented in this section provides a basis for thedose-response assessment carried out in the quantitative risk assessment.

Evaluation of the toxic potential of a chemical involves the examination of available data that relateobserved toxic effects to doses. Generally, there are two categories of information that are consideredin this part of a quantitative risk assessment:

• Information on the potential acute or chronic non-cancer effects of chemicals, and • Information on the potential for chemicals to initiate or promote cancers.

A wide variety of factors must be considered in using health effects data in qualitative or quantitativeassessments. As discussed in the following subsections, there may be a variety of relationshipsbetween dose and effects. Also, the fact that some chemicals display thresholds (i.e., there are dosesbelow which the chemical does not cause an effect) must be considered.

Non-Carcinogenic Effects. In general, non-carcinogenic effects (acute or chronic systemic) areconsidered to have threshold values, while carcinogenic effects are considered to not have thresholds.Toxicity studies for the former focus on identifying where this threshold occurs. The threshold canbe related to a reference dose (RfD). A chronic RfD is an estimate of a daily exposure level for whichpeople, including sensitive individuals, do not have an appreciable risk of suffering significant adversehealth effects. Exposure doses above an RfD could possibly cause health effects.

50

Carcinogenic Effects. Studies of carcinogenicity tend to focus on identifying the slope of the linearportion of a curve of dose versus response. A plausible upper-bound value of the slope is called thecancer slope factor (CSF) or cancer potency factor (CPF). The product of the CSF and the exposuredose is an estimate of the risk of developing cancer. In accordance with current scientific policyconcerning carcinogens, it is assumed that any dose, no matter how small, has some associatedresponse. This is called a non-threshold effect. In this assessment, the no-threshold effect was appliedto all probable carcinogens.

Toxicological Properties. The risks associated with exposure to constituents detected at OU7 area function of the inherent toxicity (hazard) of the constituents and exposure dose. This sectionaddresses the inherent toxicological properties of the constituents. The exposure doses are estimatedin the Exposure Assessment section which follows.

A distinction is made between carcinogenic and non-carcinogenic effects. Two general criteria areused to describe these effects: excess lifetime cancer risk for constituents which are thought to bepotential human carcinogens and the hazard quotient (HQ) for constituents that causenon-carcinogenic effects. For potential carcinogens, the current regulatory guidelines (USEPA,1989a) use an extremely conservative approach in which it is assumed that any level of exposure toa carcinogen could hypothetically cause cancer. This is contrary to the traditional toxicologicalapproach to toxic chemicals, in which finite thresholds are identified, below which toxic effects arenot expected to occur. This traditional approach still is applied to non-carcinogenic chemicals.

Toxicity Values. In general, CSFs, cancer classifications, RfDs, and RfCs are taken from IRIS (1996)or, in the absence of IRIS data, the USEPA Health Effects Assessment Summary Tables (HEAST)(USEPA, 1995). Because toxicity values for dermal exposure are rarely available, several adjustmentswere made to toxicity values for use in calculating dermal dose as per Region IV supplementalguidance to RAGS issued in March of 1994. The PAH CSFs were not adjusted to assess dermalexposure since the portal of entry differs in the outcome of tumors from oral and dermal exposure(USEPA, 1989a). Oral toxicity constants (both RfD and CSFs) were adjusted for dermal use via theapplication of oral absorption efficiency values obtained from Region IV supplemental guidance toRAGS issued in March of 1994. The factors used to correct both exposure dose calculations fordermal absorption from soil and the factors used to adjust oral toxicity constants (RfDs and CSFs)for use in calculating risks and hazard indices via dermal exposure are provided in Table 2-33.Unadjusted oral and inhalation RfDs are provided in Table 2-34. CSFs, cancer type or tumor sites,and

TABLE 2-33

DERMAL AND ORAL ABSORPTION EFFICIENCIESFOR CHEMICALS OF POTENTIAL CONCERN AT

OU-7, ENTOMOLOGY STORAGE AREAHomestead Air Reserve Base, Florida

Constituents

Adsorption Efficiencies

Dermal a Oral b

VOCSBenzene 0.01 0.80 cBromodichloromethane 0.01 0.80 cChloroform 0.01 0.80 cDibromochloromethane 0.80 c

BNAsBenzo(a)anthracene 0.01 0.50 cBenzo(a)pyrene 0.01 0.50 cBenzo(b)fluoranthene 0.01 0.50 cDibenzo(a,h)anthracene 0.01 0.50 c

TPHs (as n-nonane)

PesticidesAlpha-BHC 0.01 0.50 cChlordane isomers 0.01 0.50 cDDD 0.01 0.50 cDDE 0.01 0.50 cDDT 0.01 0.50 cEndrin Ketone 0.01 0.50 cHeptachlor epoxide 0.01 0.50 c

MetalsAluminum 0.001 0.02 cAntimony 0.001 0.02 cArsenic 0.001 0.02 cBarium 0.001 0.02 cCadmium 0.001 0.02 cChromium (VI) 0.001 0.02 cLead 0.001 0.02 cManganese 0.001 0.02 cSilver 0.001 0.02 cVanadium 0.001 0.02 c

Notes:a Used to adjust dermal dose calculation for absorption from soil as per Region IV

Supplemental Guidance to RAGS Bulletin, Vol. 1 No. 1, USEPA, Atlanta, Georgia,March 1994.

b Used to adjust oral toxicity constants (RfDs and CPFs) to estimate effects via dermalexposure. Values as per Region IV Supplemental Guidance to RAGS Bulletin, Vol. 1 No.1, USEPA, Atlanta, Georgia, March 1994.

c default valued National Research Council (1982).

TABLE 2-34

REFERENCE DOSES FOR CHEMICALS OF POTENTIAL CONCERN ATOU-7, ENTOMOLOGY STORAGE AREA

Homestead Air Reserve Base, Florida

Constituent

ChronicOral RfD

(mg/kg/day)

SubchronicOral RfD

(mg/kg/day)

ChronicInhalation RfD

(mg/kg/day)

SubchronicInhalation RfD

(mg/kg/day)

VOCSBenzene 3.00E-04 a NA 1.70E-03 a NABromodichloromethane 2.00E-02 b 2.00E-02 c NA NAChloroform 1.00E-02 b 1.00E-02 c NA NADibromochloromethane 2.00E-02 b 2.00E-01 c NA NA

BNAsBenzo(a)anthracene(1) 3.00E-02 b 3.00E-01 c NA NABenzo(a)pyrene(1) 3.00E-02 b 3.00E-01 c NA NABenzo(b)fluoranthene(1) 3.00E-02 b 3.00E-01 c NA NADibenzo(a,h)anthracene(1) 3.00E-02 b 3.00E-01 c NA NA

TPHs (as n-nonane)(2) 6.00E-01 d NA NA NA

PesticidesAlpha-BHC (3) 3.00E-04 b 3.00E-04 c NA NAChlordane isomers 6.00E-05 b 6.00E-05 c NA NADDD (4) 5.04E-04 b 5.04E-04 c NA NADDE (4) 5.04E-04 b 5.04E-04 c NA NADDT 5.04E-04 b 5.04E-04 c NA NAEndrin Ketone (5) 3.00E-04 b 3.00E-04 c NA NAHeptachlor epoxide 1.30E-05 c 1.30E-05 c NA NA

MetalsAluminum 1.00E+00 a NA NA NAAntimony 4.00E-04 b 4.00E-04 c NA NAArsenic 3.00E-04 b 3.00E-04 c NA NABarium 7.00E-02 b 7.00E-02 c 1.00E-04 c 1.00E-03 cCadmium (water) 5.00E-04 b NA NA NACadmium (food) 1.00E-03 b NA NA NAChromium (VI) 5.00E-03 b 2.00E-02 c NA NALead NA NA NA NAManganese 2.40E-02 b NA 1.43E-05 b NASilver 5.00E-03 b 5.00E-03 c NA NAVanadium 7.00E-03 c 7.00E-03 c NA NA

a ECAOb IRIS, 1996c USEPA, 1995d Massachusetts DEP, 1994(1) The pyrene RfD was used as a surrogate for PAH RfDs(2) The n-Nonane RfD was used as a surrogate for TPHs RfD(3) The gamma-BHC RfD was used as a surrogate for the alpha-BHC RfD(4) The DDT RID was used as a surrogate for the DDD and DDE RfDs(5) The endrin RfD was used as a surrogate for the Endrin Ketone RfD

51

carcinogen classifications for the COPCs at the site are presented in Table 2-35. Derivation of theadjusted RfDs and CSFs is shown in Table 2-36.

There are no USEPA-verified acceptable doses (i.e., RfDs) for lead. Considerable controversycurrently exists concerning the appropriate acceptable doses for lead. The best method for evaluatingexposure to lead is through the measurement of lead in blood or blood lead levels. Lead wasevaluated in this risk assessment based on acceptable blood lead levels for young children using theUSEPA (1994a) IEUBK model (LEAD 0.99d).

USEPA Region IV has adopted an approach to TPH developed by the State of Massachusetts DEP(Massachusetts DEP, 1994). This approach uses the toxicity values of certain hydrocarboncompounds (e.g. n-hexane, n-nonane, eicosane) as surrogate toxicity values for fractions of TPH(Andrews and Snyder, 1991). The toxicity of hydrocarbons tends to decrease with increasing carbonchain length. n-Hexane has an RfD of 0.06, n-nonane an RfD of 0.6, and eicosane an RfD of 6.

After review and discussion with USEPA Region IV, n-nonane was used to calculate noncancer risksassociated with exposure to Total Recoverable Petroleum Hydrocarbons (TRPHs) and tentativelyidentified compounds (TICs) shown to be petroleum related. The toxicity of hydrocarbons generallydecreases as chain length increases (Andrews and Snyder, 1991). The light-end hydrocarbons (e.g.,n-hexane) present in TPH tend to attenuate by weathering faster than heavier components, leavingthe long-chain, less toxic components of TPH. Thus, use of n-nonane as a toxicity surrogate for theTPH represents a conservative (protective) approach.

2.7.5 Risk Characterization

This section of the risk assessment describes how calculated exposure doses are converted into healthrisks. This section characterizes risks as part of a quantitative risk assessment for the site. Riskcharacterization involves the integration of health effects information developed as part of thedose-response assessment with exposure estimates developed as part of the exposure assessment. Theresult is a quantitative estimate of chronic and noncarcinogenic risks based on the presumption thata threshold dose is required to elicit a response, as well as a quantitative estimate of carcinogenic riskspresumed to exist regardless of the dose. These estimates are usually presented in either probabilisticterms (e.g., one-in-one-million), or with reference to specific benchmark or threshold levels. Becauserisk estimates are based on a combination of measurements and assumptions, it is important to

TABLE 2-35

CANCER SLOPE FACTORS, TUMOR SITES, AND USEPA CANCERCLASSIFICATIONS FOR CHEMICALS OF POTENTIAL CONCERN AT

OU-7, ENTOMOLOGY STORAGE AREAHomestead Air Reserve Base, Florida

CSF (mg/kg/day)-1 Tumor Site USEPAClassificationConstituent Oral Inhalation Oral Inhalation

VOCsBenzene 2.9E-02 b 2.9E-02 b Leukemia Leukemia ABromodichloromethane 6.2E-02 b NA kidney NA B2Chloroform 6.1E-03 b 8.1E-02 c kidney liver B2Dibromochloromethane 8.4E-02 b NA liver NA C

BNAsBenzo(a)anthracene (1) 7.3E-01 b 6.1E-01 a stomach respiratory tract B2Benzo(a)pyrene 7.3E+00 b 6.1E+00 a stomach respiratory tract B2Benzo(b)fluoranthene (1) 7.3E-01 b 6.1E-01 a stomach respiratory tract B2Didenzo(a,h)anthracene (1) 7.3E+00 b 6.1E+00 a stomach respiratory tract B2

PesticidesAlpha-BHC 6.3E+00 b 6.3E+00 c liver liver B2Chlorodane Isomers 1.3E+00 b 1.3E+00 b liver liver B2DDD 3.4E-01 b NA liver NA B2DDE 3.4E-01 b NA liver NA B2Heptachlor epoxide 9.1E+00 b 9.1E+00 c liver liver B2

MetalsArsenic 1.5E+00 b 1.5E+01 b skin respiratory tract ACadmium NAP 6.3E+00 b NAP respiratory tract B1Chromium (VI) NAP 4.1E+01 b NAP lung ALead NA NA NA NA B2

mg/kg/day Milligrams pet kilogram per day.NA Not available.NAP Not applicable since it is considered carcinogenic via inhalation only.

a ECAOb IRIS, 1996c USEPA, 1995(1) The CSF for benzo(a)pyrene was used as a surrogate value for this compound. A Toxicity Equivalency Factor

(TEF)based on the relative potency of the chemical to benzo(a)pyrene is used to adjust the benzo(a)pyrene CSF foreach carcinogenic PAH.

TABLE 2-36

ADJUSTED TOXICITY VALUES USED TO ASSESS DERMAL EXPOSURE ATOU-7, ENTOMOLOGY STORAGE AREA

Homestead Air Reserve Base, Florida

Oral Toxicity Values OralAbsorption

Dermal Toxicity Values(Adjusted Oral)

Constituent RfDo Source CsFo Source Efficiency Source RfDa CSFa

VOCsBenzene 3.0E-04 a 2.9E-02 b 0.80 d 2.4E-04 3.6E-02Bromodichloromethane 2.0E-02 b 6.2E-02 b 0.80 d 1.6E-02 7.8E-02Chloroform 1.0E-02 b 6.1E-03 b 0.80 d 8.0E-03 7.6E-03Dibromochloromethane 2.0E-02 b 8.4E-02 b 0.80 d 1.6E-02 1.1E-01

BNAsBenzo(a)anthracene 3.0E-02 c 7.3E-01 b 0.50 d 1.5E-02 1.5E+00 1Benzo(a)pyrene 3.0E-02 c 7.3E+00 b 0.50 d 1.5E-02 1.5E+01 1Benzo(b)fluoranthene 3.0E-02 c 7.3E-01 b 0.50 d 1.5E-02 1.5E+00 1Didenzo(a,h)anthracene 3.0E-02 c 7.3E+00 b 0.50 d 1.5E-02 1.5E+01 1

TPHs (as n-nonane 6.0E-01 k NA 0.50 d 3.0E-01 NA

PesticidesAlpha-BHC 3.0E-04 f 6.3E+00 b 0.50 d 1.5E-04 1.3E+01Chlorodane Isomers 6.0E-05 b 1.3E+00 b 0.50 d 3.0E-05 2.6E+00DDD 5.0E-04 g 2.4E-01 b 0.50 d 2.5E-04 4.8E-01DDE 5.0E-04 g 3.4E-01 b 0.50 d NA 6.8E-01DDT 5.0E-04 b 3.4E-01 b 0.50 d 2.5E-04 6.8E-01Endrin Ketone 3.0E-04 h NA 0.50 d 1.5E-04 NAHeptachlor epoxide 1.3E-05 j 9.1E+00 b 0.50 d 6.5E-06 1.8E+01

MetalsAluminum 1.0E+00 b NA 0.20 d 2.0E-01 NAAntimony 4.0E-04 b NA 0.20 d 8.0E-05 NAArsenic 3.0E-04 b 1.5E+00 b 0.95 i 2.9E-04 1..6E+00Barium 7.0E-02 b NA 0.20 d 1.4E-02 NACadmium (water) 5.0E-04 b NAP 0.20 d 1.0E-04 NACadmium (food) 1.0E-03 b NAP 0.20 d 2.0E-04 NAChromium (VI) 5.0E-03 b NAP 0.20 d 1.0E-03 NALead NA b NA 0.20 d NA NAManganese 2.4E-02 b NA 0.20 d 4.8E-03 NASilver 5.0E-03 b NA 0.20 d 1.0E-03 NAVanadium 7.0E-03 b NA 0.20 d 1.4E-03 NA

CSFa Adjusted cancer slope factor (mg/kg/day) ^ - 1.CSFo Oral cancer slope factor (mg/kg/day) ^ - 1.NA Not available.NAP Not applicable. Carcinogenic only by inhalation route.RfDa Adjusted reference dose (mg/kg/day).RfDo Oral reference dose (mg/kg/day).

a ECAOb IRISc Pyrcne RfD used as surrogate for PAH RfDs.d Default Value.e N-Nonane RID used as surrogate for TPH RfDf gamma-BHC RfD used as surrogate for alpha-BHC RfD9 DDT RfD used as surrogate for DDD and DDE RfDs.h Endrin RfD used as surrogate for Endrin Ketone RfDi National Research Council (1982)j USEPA (1995)k Massachusetts DEP, 19941 PAH slope factors were not adjusted to assess dermal exposure since the portal of entry differs in the outcome of tumors from oral and dermal exposure

(USEPA. 1989a).

52

provide information on sources of uncertainty in risk characterization. The key elements of riskcharacterization included in this section are: an estimation of human dose, an estimation of risk, apresentation of risk, and an uncertainty analysis.

2.7.5.1 Carcinogenic Risks. Public health risks are evaluated separately for carcinogenic andnon-carcinogenic effects. The excess lifetime cancer risk is an estimate of the increased risk of cancerwhich results from lifetime exposure, at specified average daily dosages, to constituents detected inmedia at the site. Excess lifetime cancer risk, equal to the product of the exposure dose and the slopefactor, is estimated for each known, probable, or possible carcinogenic constituent in each medium.The risk values provided in this report are an indication of the increased risk, above that applying tothe general population, which may result from the exposure scenarios described in the ExposureAssessment Section 2.7.3. The risk estimate is considered to be an upperbound estimate; therefore,it is likely that the true risk is less than that predicted by the model. Current regulatory methodologyassumes that excess lifetime cancer risks can be summed across routes of exposure and constituentsto derive a “Total Site Risk” (USEPA, Risk Assessment Guidance for Superfund Sites, 1989a). TheUSEPA OSWER Directive 9355.0-30, Role of the Risk Assessment in Superfund Remedy SelectionDecisions (1991e) has stated that sites with an excess lifetime cancer risk less than 10 -4 (1 in 10,000)generally do not warrant remedial action. However, the state of Florida’s target cancer risk is 10 -6.

The incremental risk is calculated for each exposure scenario based on the following basic equation:

Cancer Risk = Exposure Dose x Slope Factor

where the slope factor (SF) is in units of (mg/kg/day) -1 based on a compound specific cancer bioassaydose response curve.

The exposure dose is adjusted over a 70-year lifetime. The summation of dose is in keeping with theconcept that for genotoxic agents there exists no threshold dose and implies that total, lifetimeexposure is of greater importance than the actual dose during the exposure event(s). Ingestion andinhalation risks are calculated separately since compounds often have different SFs for differing routesof exposure. The different SFs relate to the pharmacokinetics inherent in each chemical/organ and thespecific routes of uptake.

Slope factors are derived by EPA in an intentionally conservative way, that is, the actual risk is notexpected to exceed the predicted risk, and could be considerably lower. Cancer risks

53

calculated using these conservative slope factors and reasonable maximum exposure estimates areupper bound estimates of excess cancer risk potentially arising from exposure to the chemicals inquestion. A number of assumptions have been made in the derivation of these values, many of whichare likely to overestimate exposure and toxicity. The actual incidence of excess cancers is likely tobe lower than these estimates and may be zero.

Lifetime daily intakes, using an averaging time of up to 70 years, effectively prorates the totalcumulative dose over a lifetime. This approach is based on the assumption for carcinogens that a highdose received over a short period of time at any age is equivalent to a corresponding low dosereceived over a lifetime (USEPA, 1989a). This assumption is unlikely to be true for all carcinogens,and introduces uncertainty into the assessment of potential risk. This assumption may also lead to anoverestimate or underestimate of potential risk, depending upon the actual timing of exposure andthe mechanism of action of individual carcinogens.

The magnitude of cancer risk relative to Superfund site remediation goals in the National ContingencyPlan ranges from 10 -4 (one-in-ten-thousand) to 10-6 (one-in-one-million) depending on the site,proposed usage, and chemicals of concern (USEPA, 1989a). Within this range, the level of risk whichis considered to be acceptable at a specific site is a risk management decision and is decided on acase-specific basis. It is generally accepted that risks above this range require attention. Theone-in-a-million level of risk (expressed as IE-06) is often referred to as the de minimis level of risk;risks calculated below this range would not require attention. The IE-06 risk level does not equateto an actual cancer incidence of one-in-a-million. For substances that may cause cancer, the riskassessment process uses animal data to predict the probability of humans developing cancer over a70-year lifetime. The numbers are given as upper bounds; the real risk is expected to be less. Theone-in-a-million risk level is a theoretical prediction that no more than one person out of a millionlifetimes would contract cancer due to an environmental exposure. By the way of comparison, theaverage person in the U.S. incurs a background risk of cancer (from all causes) of about one chancein four (0.25). Adding a risk of 0.000001 to a background risk of 0.25 is of little significance to anysingle individual. These small risk levels may be of concern only if the exposed population includesmany millions of people.

2.7.5.2 Chronic Health Risks. The HQ is the ratio of the estimated exposure dose to the RfD.This ratio is used to evaluate non-carcinogenic health effects due to exposure to a constituent. An HQgreater than I indicates that the estimated exposure dose for that constituent exceeds acceptable levelsfor protection against non-carcinogenic effects.

54

Although an HQ of less than 1 suggests that non-carcinogenic health effects should not occur, an HQof slightly greater than 1 is not necessarily an indication that adverse effects will occur. The sum ofthe HQs is termed the hazard index (HI). Current regulatory methodology assumes that HIs can besummed across exposure routes for all media at the site to derive a “Total Site Risk.” The USEPAOSWER Directive 9355.0-30, Role of Risk Assessment in Superfund Remedy Selection Decisions(1991e) has stated that sites with a non-carcinogenic HQ less than 1.0 generally do not warrantremedial action.

The USEPA has developed a set of health based benchmark numbers, called reference doses, orRfDs, as guideposts in a risk assessment. Reference doses are an adaptation of the earliertoxicological measure of “acceptable daily dose” or ADI The unit of a reference dose is mgcontaminant/kg body weight/day. The potential for adverse effects on human health (other thancancer) is evaluated by comparing an intake over a specific time period with a reference dose derivedfor a similar exposure period.

The hazard index is the ratio (unitless) of the estimated exposure dose (D) of a compound to areference dose (RfD) judged to be without adverse effects given long-term exposure. Thus, the indexis used as a measure of potential noncarcinogenic health risks. Due to the margin of safety built intothe RfD value, exceedence of the number has no immediate meaning with regard to specific healtheffects, the frequency of effects, or the magnitude of effects. However, exceedcnce of the numbershould serve as an indicator that the potential for unacceptable exposure does exist and furtherevaluation needs to be considered. The effects of noncarcinogens in the body vary greatly with regardto potential target organs, threshold dose, and “severity” of effect. Therefore, the individual toxicityfor each compound needs to be assessed.

If the hazard index is less than 1.0, then no chronic health effects are expected to occur. If the hazardindex is greater than 1.0, then adverse health risks are possible. In the case of noncarcinogenic effects,chronic exposure below a threshold dose results in a non-response or a diminished response.

2.7.5.3 Risks Associated With Exposure to Groundwater. Risks for a hypothetical futureresident exposed to groundwater are shown in Table 2-37. The excess lifetime cancer risk and HI are2E-02 and 90, respectively. The excess lifetime cancer risk level associated with hypothetical futureresident conditions at the site is above the USEPA remediation-based risk benchmarks forcarcinogens (10-4 to 10-6) and above the state of Florida’s criterion of IE06. The hazard index alsoexceeds the risk benchmark of one.

TABLE 2-37

GROUNDWATER INGESTION EXPOSUREDOSES AND RISK CALCULATIONS

FOR A HYPOTHETICAL FUTURE ADULT RESIDENT ATOU-7, ENTOMOLOGY STORAGE AREA

Homestead Air Reserve Base, Florida

ConstituentCgw

(mg/L)GWExD

(mg/kg-day)ToxicityValues

CalculatedRisk

CANCER EFFECTS CSFo

VOCsBromodichloromethane 0.004 4.7E-05 6.2E-02 2.9E-06Chloroform 0.009 1.1E-04 6.1E-03 6.4E-07Dibromochloromethane 0.002 2.3E-05 8.4E-02 2.0E-06

PesticidesAlpha-BHC 0.00003 3.5-07 6.3E+00 2.2E-06DDD 0.01 1.2E-04 2.4E-01 2.8E-05

MetalsArsenic 0.96 1.1E-02 1.50E+00 1.7E-02Cadmium 0.0125 1.5E-04 NAP NAPChromium 0.026 3.1E-04 NAP NAPLead 0.024 2.8E-04 - -

- -ELCR = 2E-02

NON-CANCER EFFECTSRfDo

VOCsBromodichloromethane 0.004 1.1E-04 2.00E-02 5.5E-03Chloroform 0.009 2.5E-04 1.00E-02 2.5E-02Dibromochloromethane 0.002 5.5E-05 2.00E-02 2.7E-03

TPHs 0.882 2.4E-02 6.00E-01 4.0E-02

Pesticides 0.0003 8.2E-07 3.00E-04 2.7E-04Alpha-BHC 0.01 2.7E-04 5.00E-04 5.5E-01DDD

MetalsAluminum 4.3 1.2E-01 1.00E+00 1.2E-01Arsenic 0.96 2.6E-02 3.00E-04 8.8E+01Cadmium 0.0125 3.4E-04 5.00E-04 6.8E-01Chromium (VI) 0.026 7.1E-04 5.00E-03 1.4E-01Lead 0.024 6.6E-04 - -Manganese 0.099 2.7E-03 2.40E-02 5.4E-01

HI = 9E+01

- Insufficient data; USEPA-verified toxicity value not available.NAP Cancer slope factor and/or reference dose applies to inhalation pathway only,

not to ingestion.Cgw Constituent exposure point concentration in groundwater in milligrams per

liter (mg/L) (see Table 4-2).GWExD Ground-water exposure dose in milligrams per kilogram per day (mg1kg/day).CSFo Cancer Slope Factor, OralRfDo Reference Dose, OralELCR Excess lifetime cancer risk.HI Hazard index (sum of the hazard quotients).

55

In accordance with current USEPA Region IV guidance (USEPA, 1995d), the inhalation and dermalexposure to VOCs during showering are assumed to be equivalent to the ingestion dose. This is basedon a growing body of evidence that risk estimates from ingestion of VOCs in potable water, inhalationof volatiles from showering, and dermal exposure to volatiles during showering or bathing are similar(Andelman, 1985; Andelman, et.al., 1986, 1987; McKone, 1987, and Jo, et.al., 1990). Given thisassumption, risks via the inhalation and dermal routes for groundwater contact can be calculated usingthe oral dose (mg/kg/day-1) and multiplying by the inhalation slope factor for carcinogens and dividingby the RfCs for noncarcinogens. No inhalation RfCs were available for bromodichloromethane,chloroform, and dibromochloromethane, thus, oral RfDs are used for these compounds. Therefore, thetotal risk via groundwater contact including oral, dermal and inhalation exposures is 2E-02 for cancerrisk and 90 for noncancer risk. Inorganics, including arsenic are not expected to volatilize from the waterdroplet, thus, the primary exposure routes via groundwater use would be ingestion and to a small degreedermal. The dermal dose is expected to be two to three orders of magnitude less than oral dose.

The primary contributor to the carcinogenic risk estimate is arsenic. This compound was detected in fiveof five samples at a range of concentrations of 25 µg/l to 960 µg/L. Only two of the samples containedconcentrations of arsenic below the state and federal drinking water standard of 50 µg/l. The arsenic risklevel is based on unfiltered samples; therefore, this level probably overestimates concentrations in ahypothetical potable well. Finally, as stated in the exposure section, future potable use of the groundwaterat the site is unlikely because of the high level of dissolved solids associated with the salt-water intrusion.

The pesticide DDD has a cancer risk estimate of 3E-05. DDD was detected in three out of fivegroundwater samples. Compounds with cancer risk estimates greater than IE-06 includebromodichloromethane, dibromochloromethane, and alpha-BHC. These compounds were detected inone out of five groundwater samples. As stated in the exposure section, future potable use of thegroundwater at the site is unlikely because of the high level of dissolved solids associated with thesalt-water intrusion.

2.7.5.4 Risks Associated With Exposure to Soils. Base Worker. Risks for a potential current baseworker who regularly accesses OU-7 are calculated in Table 2-38. The excess lifetime cancer risk andHI are 2E-6 and 0.02, respectively. These risk levels are below the USEPA remediation-based riskbenchmarks and slightly above the state of Florida’s target risk of 1E-06.

TABLE 2-38

SOIL EXPOSURE DOSES AND RISK CALCULATIONSFOR A POTENTIAL CURRENT BASE WORKER AT

OU-7, ENTOMOLOGY STORAGE AREAHomestead Air Reserve Base, Florida

Cs SExDo SExDd SExDi Calculated(mg/kg) (mg/kg-day) (mg/kg-day) Toxicity Values Risk/HI

Constituent

CANCER EFFECTS CSFo CSFd CSFi

VOCsBenzene 0.024 8.7E-10 5.5E-10 3.8E-08 2.9E-02 3.6E-02 2.9E-02 1.1E-09

BNAsBenzo(a)anthracene 1.4 5.1E-08 3.2E-08 1.1E-12 7.3E-01 7.3E-01 6.1E-01 6.1E-08Benzo(a)pyrene 0.97 3.5E-08 2.2E-08 7.4E-13 7.3E+00 7.3E+00 6.1E+00 4.2E-07Benzo(b)fluoranthene 1.362 4.9E-08 3.1E-08 1.0E-12 7.3E-01 7.3E-01 6.1E-01 5.9E-08Didenzo(a,h)anthracene 0.28 1.0E-08 6.4E-09 2.1E-13 7.3E+00 7.3E+00 6.1E+00 1.2E-07

Pesticides/PCBsChlorodane Isomers 1.143 4.2E-08 2.6E-08 8.7E-13 1.3+00 2.6E+00 1.3E+00 1.2E-07DDE 0.762 2.8E-08 1.8E-08 5.8E-13 3.4E-01 6.8E-01 3.4E-01 2.1E-08DDT 1.541 5.6E-08 3.5E-08 1.2E-12 3.4E-01 6.8E-01 3.4E-01 4.3E-08Heptachlor Epoxide 0.0077 2.8E-10 1.8E-10 5.9E-15 9.1E+00 1.8E+01 9.1E+00 5.8E-09

MetalsArsenic 18 6.5E-07 4.1E-08 1.4E-11 1.5E+00 1.6E+00 1.5E+01 1.0E-06Chromium(VI) 26.7 9.7E-07 6.1E-08 2.0E-11 NAP NAP 14.1E+01 8.4E-10

ELCR 2E-06NON-CANCER EFFECTS

RfDo RfDd RfDiVOCsBenzene 0.024 2.4E-09 1.5E-09 1.1E-07 3.0E-04 2.4E-04 1.7E-03 7.7E-05

BNAsBenzo(a)anthracene 1.4 1.4E-07 9.0E-08 3.0E-12 3.0E-02 1.5E-02 3.0E-02 1.1E-05Benzo(a)pyrene 0.97 9.9E-08 6.2E-08 2.1E-12 3.0E-02 1.5E-02 3.0E-02 7.4E-06Benzo(b)fluoranthene 1.362 1.4E-07 8.8E-08 2.9E-12 3.0E-02 1.5E-02 3.0E-02 1.0E-05Didenzo(a,h)anthracene 0.28 2.8E-08 1.8E-08 6.0E-12 3.0E-02 1.5E-02 3.0E-02 2.2E-06

Pesticides/PCBsChlorodane Isomers 1.143 1.2E-07 7.4E-08 2.4E-12 6.0E-05 3.0E-05 6.0E-05 4.4E-03DDE 0.762 7.8E-08 4.9E-08 1.6E-12 5.0E-04 2.5E-04 5.0E-04 3.5E-04DDT 1.542 1.6E-07 9.9E-08 3.3E-12 5.0E-04 2.5E-04 5.0E-04 7.1E-04Endrin Ketone 0.0561 5.7E-09 3.6E-09 1.2E-13 3.0E-04 1.5E-04 3.0E-04 4.3E-05Heptachlor epoxide 0.0077 7.8E-10 5.0E-10 1.6E-14 1.3E-05 6.5E-06 1.3E-05 1.4E-04

MetalsAluminum 7,501 7.6E-04 4.8E-05 1.6E-08 1.0E+00 2.0E-01 1.0E+00 1.0E-03Arsenic 18 1.8E-06 1.2E-07 3.8E-11 30E-04 2.9E-04 3.0E-04 6.5E-03Barium 65 6.6E-06 4.2E-07 1.4E-10 7.0E-02 1.4E-02 1.0E-04 1.3E-04Chromium(VI) 26.7 2.7E-06 1.7E-07 5.7E-11 5.0E-03 1.0E-03 5.0E-03 7.2E-04Manganese 91 9.3E-06 5.9E-07 1.9E-10 2.4E-02 4.8E-03 1.4E-05 5.2E-04Silver 10.4 1.1E-06 6.7E-08 2.2E-11 5.0E-03 1.0E-03 5.0E-03 2.8E-04Vanadium 11.8 1.2E-06 7.6E-08 2.5E-11 7.0E-03 1.4E-03 7.0E-03 2.3E-04

HI 2E-02

ELCR Excess lifetime cancer risk. CSFo Cancer Slope Factor, OralHl Hazard index (sum of the hazard quotients) CSFd Cancer Slope Factor. DermalCs Concentration of chemical in soil (mg/kg) CSFi Cancer Slope Factor, InhalationSExDo Soil exposure dose, oral route RfDo Reference Dose, OralSExDd Soil exposure dose, dermal route RfDd Reference Dose.,DermalSExDi Soil exposure dose, inhalation route RfDi Reference Dose, InhalationNAP Not applicable., carcinogenic via inhalation pathway only

56

Hypothetical Future Residents. The risks for hypothetical future residents exposed to onsite soilsare calculated in Tables 2-39 (adult, 24-year exposure period) and 2-40 (young child, 6-year exposureperiod). For an adult, the estimated excess lifetime cancer risk and HI are 2E-05 and 0.2,respectively. The excess lifetime cancer risk and HI for the child are 5E-05 and 2, respectively. Theadult cancer risk estimates and the adult hazard index are below the USEPA remediation-based riskbenchmark, and above the state of Florida target risk of 1E-06. The child cancer risk does not exceedthe USEPA one in ten thousand upperbound but does exceed the state of Florida target risk of 1E-06.The hazard index for the child is above the benchmark of 1.0. The principal contributors to theexcess cancer risk level are arsenic, PAHs, and chlordane. The principal contributors to the hazardindex are arsenic and chlordane.

Arsenic was detected in 30 of 31 surface soil samples in concentrations ranging from 0.49 to 44.5mg/kg. Although this exceeds the site-specific background concentration of 1.6 mg/kg, this range ofconcentrations is comparable to reported literature values for typically uncontaminated soils and thecommon range for eastern soils in the U.S. (GRI, 1987, Shacklette and Boerngen, 1984). PAHs weredetected in 3 to 6 of the 15 samples collected in surface soils. The sum of the maximum PAHconcentrations detected is 4.5 ppm. This concentration is within the range of concentrations reportedfor urban soils of 0.06 to 5.8 ppm (Menzie, et. aL, 1992). Chlordane was detected in 15 of 25samples in concentrations ranging from 0.07 to 3.5 ppm. The individual excess cancer riskattributable to chlordane is at the benchmark of 1E-6 for the adult resident and at 2E-6 for the child.However, the maximum concentration detected is well above levels detected in areas unaffected byindustrial activities (U.S. National Soils Monitoring Program, 1970-72). But the detection of thiscompound is not unusual, as this site is a former pesticide storage area and chlordane is still used inthe -control of underground termites. The hazard index for the child resident exceeds the benchmarkof one due to the sum of compounds detected. No individual noncancer risk estimate is greater thanone.

Hypothetical Future Construction Worker. Risks for future construction workers who would accessOU-7 are calculated in Table 2-41. The risks are estimated for construction worker exposure tosurface and subsurface soils via inhalation and ingestion routes of exposure. The excess lifetimecancer risk and HI for ingestion and inhalation of surface soil are 3E-6 and 0.5, respectively. Theexcess lifetime cancer risk and HI for ingestion and inhalation of subsurface soils are 3E-6 and 0.6,respectively. The cancer risk estimate is slightly above the state of Florida target cancer risk, butbelow the USEPA remediation-

TABLE 2-39

SOIL EXPOSURE DOSES AND RISK CALCULATIONSFOR A HYPOTHETICAL CURRENT BASE WORKER AT

OU-7, ENTOMOLOGY STORAGE AREAHomestead Air Reserve Base, Florida

Cs SExDo SExDd SExDi Calculated(mg/kg) (mg/kg-day) (mg/kg-day) Toxicity Values Risk/HI

Constituent

CANCER EFFECTS CSFO CSF CFI

V.C.Benzene 0.024 1.1E-08 3.6E-09 9.9E-07 2.9E-02 3.6E-02 2.9E-02 1.1E-09

BNAsBenzo(a)anthracene 1.4 6.6E-07 2.1E-07 2.7E-11 7.3E-01 7.3E-01 6.1E-01 6.3E-07Benzo(a)pyrene 0.97 4.6E-07 1.4E-07 1.9E-11 7.3E+00 7.3E+00 6.1E+00 4.4E-06Benzo(b)fluoranthene 1.362 6.4E-07 2.0E-07 2.7E-11 7.3E-01 7.3E-01 6.1E-01 6.1E-07Didenzo(a,h)anthracene 0.28 1.3E-07 4.2E-08 5.5E-12 7.3E+00 7.3E+00 6.1E+00 1.3E-06

Pesticides/PCBsChlorodane Isomers 1.143 5.4E-07 1.7E-07 2.2E-11 1.3+00 2.6E+00 1.3E+00 1.1E-06DDE 0.762 3.6E-07 1.1E-07 1.5E-11 3.4E-01 6.8E-01 3.4E-01 2.0E-07DDT 1.541 7.2E-07 2.3E-07 3.0E-11 3.4E-01 6.8E-01 3.4E-01 4.0E-07Heptachlor Epoxide 0.0077 3.6E-09 1.1E-09 1.5E-13 9.1E+00 1.8E+01 9.1E+00 5.4E-08

MetalsArsenic 18 8.5E-06 2.7E-07 3.5E-10 1.5E+00 1.6E+00 1.5E+01 1.3E-05Chromium(VI) 26.7 1.3E-05 4.0E-07 5.2E-10 NAP NAP 4.1E+01 2.2E-08

ELCR 2E-05NON-CANCER EFFECTS

RfDo RfDd RfDiVOC.Benzene 0.024 3.3E-08 1.0E-08 2.9E-06 3.0E-04 2.4E-04 1.7E-03 1.8E-03

BNAsBenzo(a)anthracene 1.4 1.9E-06 6.1E-07 8.0E-11 3.0E-02 1.5E-02 3.0E-02 1.0E-04Benzo(a)pyrene 0.97 1.3E-06 4.2E-07 5.6E-11 3.0E-02 1.5E-02 3.0E-02 7.2E-05Benzo(b)fluoranthene 1.362 1.9E-06 5.9E-07 7.8E-11 3.0E-02 1.5E-02 3.0E-02 1.0E-04Didenzo(a,h)anthracene 0.28 3.8E-07 1.2E-07 1.6E-11 3.0E-02 1.5E-02 3.0E-02 2.1E-05

Pesticides/PCBsChlorodane Isomers 1.143 1.6E-06 4.9E-07 6.5E-11 6.0E-05 3.0E-05 6.0E-05 4.3E-02DDE 0.762 1.0E-06 3.3E-07 4.4E-11 5.0E-04 2.5E-04 5.0E-04 3.4E-03DDT 1.541 2.1E-06 6.7E-07 8.8E-11 5.0E-04 2.5E-04 5.0E-04 6.9E-03Endrin Ketone 0.0561 7.7E-08 2.4E-08 3.2E-12 3.0E-04 1.5E-04 3.0E-04 4.2E-04Heptachlor epoxide 0.0077 1.1E-08 3.3E-09 4.4E-13 1.3E-05 6.5E-06 1.3E-05 1.3E-03

MetalsAluminum 7,501 1.0E-02 3.2E-04 4.3E-07 1.0E+00 2.0E-01 1.0E+00 1.2E-02Arsenic 18 2.5E-05 7.8E-07 1.0E-09 3.0E-04 2.9E-04 3.0E-04 8.5E-02Barium 65 8.9E-05 2.8E-06 3.7E-09 7.0E-02 1.4E-02 1.0E-04 1.5E-03Chromium(VI) 26.7 3.7E-05 1.2E-06 1.5E-09 5.0E-03 1.0E-03 5.0E-03 8.5E-03Manganese 91 1.2E-04 3.9E-06 5.2E-09 2.4E-02 4.8E-03 1.4E-05 6.4E-03Silver 10.4 1.4E-05 4.5E-07 6.0E-10 5.0E-03 1.0E-03 5.0E-03 3.3E-03Vanadium 11.8 1.6E-05 5.1E-07 6.8E-10 7.0E-03 1.4E-03 7.0E-03 2.7E-03

HI 2E-01

ELCR Excess lifetime cancer risk. CFO Cancer Slope Factor, OralHI Hazard index (sum of the hazard quotients) CSF Cancer Slope Factor, DermalCs Concentration of chemical in soil (mg/kg) CFI Cancer Slope Factor, InhalationSExDo Soil exposure dose, oral route RfDo Reference Dose, OralSExDd Soil exposure dose, dermal route RfDd Reference Dose.,DermalSExDi Soil exposure dose, inhalation route RfDi Reference Dose, InhalationNAP Not applicable., carcinogenic via inhalation pathway only

TABLE-240

SOIL EXPOSURE DOSES AND RISK CALCULATIONSFOR A HYPOTHETICAL FUTURE CHILD RESIDENT AT

OU-7, ENTOMOLOGY STORAGE AREAHomestead Air Reserve Base, Florida

ConstituentCS

(mg/kg)SExDo

(mg/kg-day)SExDd

(mg/kg-day)SExDi

(mg/kg-day) Toxicity valuesCalculated

Risk/HI

CANCER EFFECTS CSFo CSFd CSFiVOCsBenzene 0.024 2.6E-08 4.8E-09 2.3E-06 2.9E-02 3.6E-02 2.9E-02 6.8E-08

BNAsBenzo(a)anthracene 1.4 1.5E-06 2.8E-07 3.2E-11 7.3E-01 7.3E-01 6.1E-01 1.3E-06Benzo(b)pyrene 0.97 1.1E-06 1.9E-07 2.2E-11 7.3E+00 7.3E+00 6.1E+00 9.2E-06Benzo(b)fluoranthene 1.362 1.5E-06 2.7E-07 3.1E-11 7.3E-01 7.3E-01 6.1E-01 1.3E-06Dibenzo(a,h)anthracene 0.28 3.1E-07 5.6E-08 6.4E-12 7.3E+00 7.3E+00 6.1E+00 2.6E-06

Pesticides/PCBs

Chlordane Isomers 1.143 1.3E-06 2.3E-07 2.6E-11 1.3E+00 2.6E+00 1.3E+00 2.2E-06DDE 0.762 8.4E-07 1.5E-07 1.7E-11 3.4E-01 6.8E-01 3.4E-01 3.9E-07DDT 1.541 1.7E-06 3.1E-07 3.5E-11 3.4E-01 6.8E-01 3.4E-01 7.8E-07Heptachlor Epoxide 0.0077 8.4E-09 1.5E-09 1.8E-13 9.1E+00 1.8E+01 9.1E+00 1.0E-07

MetalsArsenic 18 2.0E-05 3.6E-07 4.1E-10 1.5E+00 1.6E+00 1.5E+01 3.0E-05Chromium (VI) 26.7 2.9E-05 5.3E-07 6.1E-10 NAP NAP 4.1E+01 2.5E-08

ELCR 5E-05

NON-CANCER EFFECTS RfDo RfDd RfDi

VOCsBenzene 0.024 3.1E-07 5.6E-08 2.7E-05 3.0E-04 2.4E-04 1.7E-03 1.7E-02

BNAsBenzo(a)anthracene 1.4 1.8E-05 3.3E-06 3.7E-10 3.0E-02 1.5E-02 3.0E-02 8.1E-04Benzo(b)pyrene 0.97 1.2E-05 2.3E-06 2.6E-10 3.0E-02 1.5E-02 3.0E-02 5.6E-04Benzo(b)fluoranthene 1.362 1.7E-05 3.2E-06 3.6E-10 3.0E-02 1.5E-02 3.0E-02 7.9E-04Dibenzo(a,h)anthracene 0.28 3.6E-06 6.5E-07 7.5E-11 3.0E-02 1.5E-02 3.0E-02 1.6E-04

Pesticides/PCBsChlordane Isomers 1.143 1.5E-05 2.7E-06 3.1E-10 6.0E-05 3.0E-05 6.0E-05 3.3E-01p,p’-DDE 0.762 9.7E-06 1.8E-06 2.0E-10 5.0E-04 2.5E-04 5.0E-04 2.7E-02p,p’-DDT 1.541 2.0E-05 3.6E-06 4.1E-10 5.0E-04 2.5E-04 5.0E-04 5.4E-02Endrin Ketone 0.0561 7.2E-07 1.3E-07 1.5E-11 3.0E-04 1.5E-04 3.0E-04 3.3E-03Heptachlor Epoxide 0.0077 9.8E-08 1.8E-08 2.1E-12 1.3E-05 6.5E-06 1.3E-05 1.0E-02

MetalsAluminum 7,501 9.6E-02 1.8E-03 2.0E-06 1.0E+00 2.0E-01 1.0E+00 1.0E-01Arsenic 18 2.3E-04 4.2E-06 4.8E-09 3.0E--04 2.9E-04 3.0E-04 7.8E-01Barium 65 8.3E-04 1.5E-05 1.7E-08 7.0E-02 1.4E-02 1.0E-04 1.3E-02Chromium (VI) 26.7 3.4E-04 6.2E-06 7.1E-09 5.0E-03 1.0E-03 5.0E-03 7.5E-02Manganese 91 1.2E-03 2.1E-05 2.4E-08 2.4E-02 4.8E-03 1.4E-05 5.5E-02Silver 10.4 1.3E-04 2.4E-06 2.8E-09 5.0E-03 1.0E-03 5.0E-03 2.9E-02Vanadium 11.8 1.5E-04 2.8E-06 3.2E-09 7.0E-03 1.4E-03 7.0E-03 2.4E-02

HI 2E+00

ELCR Excess lifetime cancer risk. CSFo Cancer Slope factor, OralHI Hazard index (sum of the hazard quotients) CSFd Cancer Slope Factor, DermalCs Concentration of chemical in soil (mg/kg) CSFi Cancer Slope Factor, InhalationSExDo Soil exposure dose, oral route RfDo Reference Dose, OralSExDd Soil exposure dose, dermal route RfDd Reference Dose, DermalSExDi Soil exposure dose, inhalation route RfDi Reference Dose, InhalationNAP Not applicable, carcinogenic via inhalation pathway only.

TABLE 2-41

SOIL EXPOSURES DOSES AND RISK CALCULATIONSFOR A HYPOTHETICAL FUTURE CONSTRUCTION WORKER AT

OU-7, ENTOMOLOGY STORAGE AREAHomestead Air Reserve Base, Florida

Page 1 of 2

Cs Surface Soil Toxicity Values Surface SoilCalculated

Risk/HI

Subsurface Soil Subsurface SoilCalculated

Risk/HIConstituentSurface (mg/kg)

Subsurface(mg/kg)

SExDo(mg/kg-day)

SExDi(mg/kg-day)

SExDo (mg/kg-day)

SExDi (mg/kg-day)

CANCER EFFECTS CSFo CSFi

VOCsBenzene 0.024 Not a COPC 1.6E-09 2.1E-07 2.9E-02 2.9E-02 6.0E-09 NC NC NC

BNAsBenzo(a)anthracene 1.4 Not a COPC 9.4E-08 8.2E-13 7.3E-01 6.1E-01 6.9E-08 NC NC NCBenzo(b)pyrene 0.97 1 6.5E-08 5.7-13 7.3E+00 6.1E+00 4.8E-07 6.7E-08 5.9E-13 4.9E-07Benzo(b)fluoranthene 1.362 Not a COPC 9.1E-08 8.0E-13 7.3E-01 6.1E-01 6.7E-08 NC NC NCDibenzo(a,h)anthracene 0.28 Not a COPC 1.9E-08 1.6-13 7.3E+00 6.1E+00 1.4E-07 NC NC NC

Pesticides/PCBsChlordane Isomers 1.143 0.55 7.7E-08 6.7E-13 1.30E+00 1.30E+00 10E-07 3.7E-08 3.2E-13 4.8E-08p.p’-DDE 0.762 Not a COPC 5.1E-08 4.5-13 3.4E-01 3.4E-01 1.7E-08 NC NC NCp,p’-DDT 1.541 Not a COPC 1.0E-07 9.0E-13 3.4E-01 3.4E-01 3.5E-08 NC NC NCHeptachlor Epoxide 0.0077 Not a COPC 5.2E-10 4.5E-15 9.1E+00 9.1E+00 4.7E-09 NC NC NC

MetalsArsenic 18 20.7 1.2E-06 1.1E-11 1.5E+00 1.5E+01 1.8E-06 1.4E-06 1.2E-11 2.1E-06Chromium (VI) 26.7 13.6 1.8E-06 1.6E-11 NAP 4.1E+01 6.4E-10 9.1E-07 8.0E-12 3.3E-10

ELCR 3E-06 ELCR 3E-06

ELCR Excess lifetime cancer risk. CSFo Cancer Slope Factor, OralHI Hazard index (sum of the hazard quotients) CSFd Cancer Slope Factor, DermalCs Concentration of chemical in soil (mg/kg) CSFi Cancer Slope Factor, InhalationSExDo Soil exposure dose, oral route RfDo Reference Dose, OralSExDd Soil exposure dose, dermal route RfDd Reference Dose, DermalSExDi Soil exposure dose, inhalation routeNAP Not applicable, carcinogenic via inhalation pathway only RfDi Reference Dose, InhalationNC Not calculated, not a COPC

TABLE 2-41

SOIL EXPOSURE DOSES AND RISK CALCULATIONSFOR A HYPOTHETICAL FUTURE CONSTRUCTION WORKER AT

OU-7, ENTOMOLOGY STORAGE AREAHomestead Air Reserve Base, Florida

Page 2 of 2Cs Surface Soil Toxicity Values Surface Soil

CalculatedRisk/HI

Subsurface Soil Subsurface Soil Calculated

Risk/HIConstituent

Surface (mg/kg)

Subsurface(mg/kg)

SExDo(mg/kg-day)

SExDi(mg/kg-day)

SExDo (mg/kg-day) SExDi (mg/kg-day)

NON CANCER EFFECTS RfDo RfDi

VOCsBenzene 0.024 Not a COPC 1.1E-07 1.4E-05 3.0E-04 1.7E-03 8.8E-03 NC NC NC

BNAsBenzo(a)anthracene 1.4 Not a COPC 6.6E-06 5.8E-11 3.0E-01 3.0E-01 2.2E-05 NC NC NCBenzo(b)pyrene 0.97 1.0 4.6E-06 4.0E-11 3.0E-01 3.0E-01 1.5E-05 4.7E-06 4.1E-11 1.6E-05Benzo(b)fluoranthene 1.362 Not a COPC 6.4E-06 5.6E-11 3.0E-01 3.0E-01 2.1E-05 NC NC NCDibenzo(a,h)anthracene 0.28 Not a COPC 1.3E-06 1.2E-11 3.0E-01 3.0E-01 4.4E-06 NC NC NC

Pesticides/PCBsChlordane Isomers 1.143 0.55 5.4E-06 4.7E-11 6.0E-05 6.0E-05 8.9E-02 2.6E-06 2.3E-11 4.3E-02p.p’-DDE 0.762 Not a COPC 3.6E-06 3.1E-11 5.0E-04 5.0E-04 7.2E-03 NC NC NCp,p’-DDT 1.541 Not a COPC 7.2E-06 6.3E-11 5.0E-04 5.0E-04 1.4E-02 NC NC NCEndrin Ketone 0.0561 Not a COPC 2.6E-07 2.3E-12 3.0E-04 3.0E-04 8.8E-04 NC NC NCHeptachlor Epoxide 0.0077 Not a COPC 3.6E-08 3.2E-13 1.3E-05 1.3E-05 2.8E-03 NC NC NC

MetalsAluminum 7.501 3.328 3.5E-02 3.1E-07 1.0E+00 1.0E+00 3.5E-02 1.6E-02 1.4E-07 1.6E-02Antimony Not a COPC 14.6 NC NC 4.0E-04 4.0E-04 NC 6.9E-05 6.0E-10 1.7E-01Arsenic 18 20.7 8.5E-05 7.4E-10 3.0E-04 3.0E-04 2.8E-01 9.7E-05 8.5E-10 3.2E-01Barium 65 Not a COPC 3.1E-04 2.7E-09 7.0E-02 1.0E-03 4.4E-03 NC NC NCChromium (VI) 26.7 13.6 1.3E-04 1.1E-09 2.0E-02 2.0E-02 6.3E-03 6.4E-05 5.6E-10 3.2E-03Manganese 91 57 4.3E-04 3.7E-09 2.4E-02 1.4E-05 1.8E-02 2.7E-04 2.3E-09 1.1E-02Silver 10.4 5.6 4.9E-10 4.3E-10 5.0E-03 5.0E-03 9.8E-03 2.6E-05 2.3E-10 5.3E-03Vanadium 11.8 11 5.5E-05 4.8E-10 7.0E-03 7.0E-03 7.9E-03 5.2E-05 4.5E-10 7.4E-03

HI 5E-01 HI 6E-01

ELCR Excess lifetime cancer risk. CSFo Cancer Slope Factor, OralHI Hazard index (sum of the hazard quotients) CSFd Cancer Slope Factor, DermalCs Concentration of chemical in soil (mg/kg) CSFi Cancer Slope Factor, InhalationSExDo Soil exposure dose, oral route RfDo Reference Dose, OralSExDd Soil exposure dose, dermal route RfDd Reference Dose, DermalSExDi Soil exposure dose, inhalation route RfDi Reference Dose, InhalationNAP Not applicable, carcinogenic via inhalation pathway onlyNC Not calculated, not a COPC

57

based risk benchmarks for the cancer and noncancer risk estimates for surface and subsurface soil.Arsenic is the primary contributor to risks greater than 1E-6. However, as discussed above, thearsenic concentrations are comparable to reported literature values, but greater than site-specificbackground concentrations.

The dermal exposure of the base worker to PAHs is approximately half that by the oral route, andthe dermal exposure of the base worker to metals is an order of magnitude lower than the oralexposure. Given that the construction worker is assumed to have a much greater oral uptake of soilthan the base worker (480 mg/day compared to 50 mg/day), and the dermal exposure of the base andconstruction worker would be expected to be similar because Air Reserve Base and OSHAregulations require construction workers to wear shirts and long pants; the dermal route of exposureis considered negligible compared to other routes for the construction worker.

2.7.5.5 Lead. The USEPA has identified a 10 to 15 µg/dL blood lead level as a range of potentialconcern for health effects in children (Federal Register, 1988b). The results from the IEUBK modelusing soil and groundwater data are listed in Table 2-42. The model predicted that 99% of childrenexposed to lead at concentrations at OU-7 would have blood lead concentration below the 10 µg/dLacceptable blood lead level. For this site, the model assumes the child is exposed to a concentrationof 25 mg/kg of lead (represents the 95 % UCL) in surface soil and 24 µg/l of lead (represents themaximum concentration) in groundwater. The model used USEPA default exposure assumptions andused the EPCs calculated from the site data, conservatively assuming a lognormal distribution.

Although the maximum concentration of lead detected in unfiltered groundwater samples (24µg/1)is greater than the federal treatment technique level in drinking water (15 µg/1), this concentrationis not anticipated to be the delivered concentration in drinking water, as water treatment prior to usewould be expected to remove the metal in particulate form from water. Lead was detected in one offive groundwater samples. At present, the shallow groundwater is not used as a drinking watersupply. Further, the use of the shallow groundwater in the future as a potable supply is highlyimprobable. Saltwater intrusion under the base has caused the replacement of on-base supply wellswith off-base supply wells. So it is likely that saltwater intrusion would preclude the use ofgroundwater at OU-7 for drinking water.

In addition, the low lead concentrations in surface soil (maximum value of 43.4 mg/kg) andsubsurface soil (maximum value of 114 mg/kg) are not expected to present a significant contributionto blood lead levels in the base worker or construction worker (USEPA, 1994a).

TABLE 2-42

MODELED BLOOD LEAD LEVELS INHYPOTHETICAL CHILDREN (AGED 0 TO 6),

OU-7 ENTOMOLOGY STORAGE AREAHomestead Air Reserve Base, Florida

Medium ConcentrationaBlood Lead Levelb

Study SiteBelow

Geometric Mean

µg/dL

Percent Below

10µg/dL

Percent

15µg/dL

SS-7/OU-7 SoilAirc

Groundwater

25.0 mg/kgnegligible24µg/L

3.4 99 100

a Lesser of 95 percent UCL on the mean or maximum detected concentration.b Calculated using the USEPA model (version 0.99d) (USEPA, 1994a).c Air concentration = SPM x Cs x UC1 x UC2.

where:Cs Soil concentration (mg/kg).dL Deciliter.Kg Kilogram.m3 Cubic meter.mg Milligram.µg Microgram.SPM Suspended particulate matter (0.075 mg/m 3) (Federal Register, 1988a).UCI Unit conversion 1 (10 -6 kg/mg).UC2 Unit conversion 2 (10 3 µg/mg).

58

In both cases the potential routes of exposure to site soils (dermal, ingestion, and inhalation),combined with the limited exposure duration for these receptors compared to the child receptor,minimize the expected dose received from the soil. Further, the IUEBK model assumes that the childis the most sensitive potential receptor. Based on this premise, if child blood lead levels do not exceedrisk-based benchmarks given the conditions at the site, then adult blood lead levels would also notbe expected to exceed the risk-based benchmarks.

The levels of lead in the soil at OU-7 are not unusual. Soil surveys have found soils within 25 metersof roadway to have from 30 to 2,000 mg/kg lead above background soil concentrations.

In summary, the lead concentrations in soils and groundwater are not expected to be of concern forthe hypothetical future child resident, the current base worker, nor the future construction workerat OU-7.

2.7.5.6 Total Site Risk. A summary of the total site risk estimates for OU-7 is presented in thissection. Table 2-43 includes the hazard indices and cancer estimates for all scenarios. Potentialcurrent total site risk is equivalent to the risk estimates calculated for a potential current on-siteworker exposed to surficial soil at the site. This scenario is evaluated in Table 2-38 with an excesslifetime cancer risk of 2E-6 and an HI of 0.02.

The total hypothetical future site risk for residential use was estimated by assuming that a future childresident could live on the site (6-year period), grow up, and continue to live there as an adult (24-yearperiod), for a total residency period of 30 years. This total site risk is obtained by summing all of theresidential exposures considered in the risk assessment: groundwater ingestion by an adult resident,and soil exposure by child (6-year period) and adult (24-year period) residents. These scenarios areevaluated in Tables 2-37, 2-39, and 2-40. The combined risk across on-site pathways (groundwaterand soils) for a hypothetical future resident results in a total site excess lifetime cancer risk of 2E-02and an HI of 92.

For the hypothetical future construction worker, the total future site risk would be based on exposureto a combination of surface and subsurface soils. Exposure point concentrations were not calculatedfor combined surface and subsurface soil. In practice, the total site risk to the hypothetical futureconstruction worker would lie between the risk calculated for the surface soil and the subsurface soil,i.e., between 2.6E-06 and 2.7E-06, and hazard index between 0.5 and 0.6.

TABLE 2-43

SUMMARY TABLE OF HAZARD INDICES ANDCANCER RISKS FOR ALL SCENARIOSOU-7, ENTOMOLOGY STORAGE AREA

Homestead Air Reserve Base, Florida

ScenarioCancerEffects

HazardIndex

Groundwater Exposure for Future AdultResident (Table 5-1, Section 5.1)

2E-02 90

Soil Exposure for Current Worker(Table 5-2, Section 5.2)

2E-06 0.02

Soil Exposure for Future Adult Resident(Table 5-3, Section 5.2)

2E-05 0.2

Soil Exposure for Future Child Resident(Table 5-4, Section 5.2)

5E-05 2

Surface Soil Exposure for Future ConstructionWorker (Table 5-5, Section 5.2)

3E-06 0.5

Subsurface Soil Exposure for Future ConstructionWorker (Table 5-5, Section 5.2) 3E-06 0.6

Total Risk to Future Resident(Child and Adult) (Tables 5-1, 5-3, and 5-4, Section 5.4)

2E-02 92

Note: all risk estimates are rounded to one significant figure.

59

Uncertainties in the Risk Assessment. The uncertainty associated with a risk estimate is primarilythe combination of the uncertainties associated with the exposure estimates and the uncertainties inthe toxicity evaluation. Additional uncertainty is inherent in environmental sampling, which itselfintroduces uncertainty, largely because of the potential for uneven distribution of constituents inenvironmental media and the use of estimated data, such as J-qualified data. The rest of the discussionpresented here focuses on the uncertainties in the exposure assessment and toxicity evaluation. It alsopresents a perspective on the overall effect of uncertainties on the risk estimates for OU-7.

Risks associated with the future exposure pathways are only meaningful if the pathways arecompleted. For pathways, such as using shallow groundwater for drinking water, the probability isvery low. It is expected that saltwater intrusion in this area already precludes the use of wells in thiszone for potable supplies. Thus, use of groundwater at the site by the hypothetical future residentappears remote.

The exposure doses generally represent the reasonable maximum exposure that can be expected tooccur. Most of the parameter values used in calculating the exposure, including the exposure pointconcentrations, were selected so that there was only a five to ten percent probability that the resultingexposure would be underestimated due to an error in an individual value. The analytical data used toestimate risks from groundwater contaminants probably do not lead to significant errors. These sameconclusions can be made for soil samples. In cases where contaminated soil acts as a continuingsource of groundwater contamination or where contaminants may be produced by biodegradation,the risk may be underestimated. Likewise, exposure doses are calculated based on the assumption thatthe current conditions would remain constant throughout the exposure period. If the source iseliminated, natural attenuation processes will reduce constituent concentrations and the likelihoodof exposure, thus reducing risks for the hypothetical future exposure scenarios.

Exposure point concentrations were calculated assuming a lognormal distribution of concentrations.The entire site was used as an exposure unit. Differing ranges of different receptors were notconsidered in the calculation of exposure point concentrations, if a receptor had a smaller range thanthe size of the site. However, the small size of the site (0.13 acres), the assumption of a lognormaldistribution of data, and the use of maxima in many cases for the exposure point concentrations,means that the exposure point concentration used for COPCs in this document are conservative.

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The most important uncertainties associated with the toxicity evaluation are the absence of aquantitative dose-response relationship for developmental and reproductive effects, and the absenceof slope factors and reference doses for some compounds of concern. The developmental andreproductive toxicity of the indicator chemicals has not been quantitatively accounted for inperforming the risk assessment, because the dose-response relationship has generally not beencharacterized for the compounds of concern. Another factor which could lead to an underestimateof the total potential risk at the site is the lack of RfDs or SFs for several compounds of concern. Areview of the compounds of concern without RfDs or SFs indicates the following: calcium is anessential nutrient and unless in high doses would have low toxic potential.

The slope factors are upper bound values for a fit of carcinogenicity data to a specific mathematicalfunction (of which the function selected is in itself generally conservative with respect to othermathematical functions that fit the data equally well). Both the slope factors and reference dosesincorporate safety factors when extrapolating from animal data to humans (including sensitiveindividuals), although animals may be more sensitive to a given compound than people. Slope factorsand reference doses typically have safety factors of 100 to 1,000. There are some notable exceptionsto this, especially when there is human toxicity data available. The uncertainty factor for the RfD forarsenic is 1, implying that the chronic dose necessary to cause a toxic effect is well known (IRIS,1991). On the other hand, it is possible that some compounds (such as the VOCs) have minimumthreshold doses associated with a carcinogenic response in humans that are not observed in animalexperiments, due to the differences between rodent and human metabolism. If this is true, the slopefactors would be overestimates by one or more orders of magnitude.

Toxicity values derived from the IRIS database system were accompanied with a qualitativedescription of their “strength of evidence” as determined by the CRAVE Work Group; thecorresponding confidence in each toxicity value added to the uncertainty.

The evaluation of health effects associated with arsenic exposure is presently a very controversialarea. While existing toxicological models attempt to relate exposure levels to quantifiablecarcinogenic and toxic risk, there is no general consensus that all arsenic exposure has negativeconsequences or that a threshold level of effect does not exist. For example, recent research indicatesthat arsenic may be nutritionally essential for humans, a requirement that has been demonstrated forfour other mammalian species. The presently available technology for estimating cancer risks tohumans at low levels may not be appropriate for evaluating arsenic exposure risks.

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The Geraghty and Miller sample depths were identified as shallow or deep, which included 0 to 2 feetand 2 to 4 feet below land surface. In some instances, the IT removal action excavated soil from apoint to a depth of 3 feet. This results in an uncertainty as to how to use the GM data point. Optionsincluded: (1) assume the GM data was representative of the 3 to 4 foot depth interval which was notremoved so include the data, (2) assume the 2 to 3 foot soil which was removed and replaced withcrushed limestone has been diluted with an equal amount of limestone so use the value at 50%diluted, (3) assume the IT removal data supersedes the GM data and delete the GM data point. Thefirst option was selected.

Sample location P2-SL-0028 was noted to be on Site ST-18 and potentially removed during theexcavation and removal of underground storage tanks associated with Site ST-18 rather than OU-7.This sample had been obtained by Geraghty and Miller in 1991. Sample point P2-SL-0033 (0 to 2 and2 to 4 feet) was intended to duplicate P2-SL-0028. Both data points were excluded from this riskassessment. The surface soil arsenic concentration in P2-SL-0028 was 118 mg/kg while the arsenicin P2-SL-0033 was not analyzed. Although this point is not within the boundaries of OU-7, it is stillwithin the boundaries of the base. It is not evaluated within this RA based on the assumption that thesoils associated with this point were excavated during the UST removal at Site ST-18.

This risk assessment is conducted using data for soil left in place throughout the soil removal andnewly generated confirmation data. All excavated soils were replaced with a crushed limestone fillmaterial. Prior to import, the fill was analyzed for volatile organics, chlorinated hydrocarbons, PAHs,TPH, leachable (TCLP) chromium, lead, and cadmium. Arsenic was not an analyte and is notexpected to occur above trace levels in the limestone. Therefore, the database does not reflect thearea of the site which is “clean”. The UCL calculation is high for two reasons. The “small” numbersor one half detection limits are not present to offset high numbers in the calculation of the UCL andthe greater number of data points which would allow more confidence in the UCL are absent.

For purposes of this risk assessment, it was assumed that all of the chromium detected in media atthe site was in the hexavalent form. Under most natural conditions in soils and water containingreducing agents, the majority of chromium is in the trivalent oxidation state. Hexavalent chromiumis more toxic than trivalent chromium. Thus, the risk estimates calculated in this report for potentialexposure to chromium likely overestimate the actual risk.

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The non-carcinogenic risks associated with potential lead exposure were not evaluated in amanner similar to other chemicals in this risk assessment (for lack of an RfD). However, theintegrated exposure biokinetic/uptake (IEUBK) model developed by the USEPA (version 0.99d)was used to predict blood lead levels in young children. Although any pharmacokinetic model issubject to uncertainties, the predicted blood lead levels (which indicate potential hypotheticalfuture lead exposure at the site is not a major concern) are believed to be a reasonable estimate.

There is also considerable uncertainty associated with the toxicity of mixtures. For the most part,data about the toxicity of constituent mixtures are unavailable. Rather, toxicity studies generallyare performed using a single constituent; such is the case for the carcinogenic PAHs. Constituentspresent in a mixture can interact to yield a new constituent or one can interfere with theabsorption, distribution, metabolism, or excretion of another. Constituents may also act by thesame mechanism at the same target organ or can act completely independently. The riskassessment assumes that toxicity is additive; the excess lifetime cancer risks and HQ were eachsummed across constituents. This assumes that the mixture of constituents present at OU-7 hasneither synergistic nor antagonistic interactions and that all of the constituents have the samemechanism of action in the same target organ to produce the same toxic endpoints.

The toxicity of all compounds in groundwater and soil has been assumed to be the same as thesum of the individual effects from each compound. Neither synergistic nor antagonistic effectsresulting from the interaction of the contaminants have been considered. In addition,transformation products with greater or less severe toxic effects than chemicals discussed hereinmay form and are not accounted for in this evaluation.

Because of the arguments presented in this section, it can be stated that for those exposurescenarios which have been quantitatively evaluated and for which the most toxic and prevalentcompounds at OU-7 have reference doses and slope factors, this risk assessment is expected to beconservative, and the actual risks are expected to be less than those calculated.

2.7.5.7Development of Remedial Goal Options. As risk characterization indicated that the riskbenchmarks of IE-04 for ELCR and 1 for HI were exceeded for certain of the scenariosconsidered, remedial goal options (RGOs) have been generated for OU-7.

Operable Unit 7 has been retained by the 482nd Air Force Reserve as part of the cantonment area.As such, the site has been rebuilt as the new Base Supply, Civil Engineering, and POL

63

Operations area. This rebuilding includes a new civil engineering complex building, three shops, astorage area, miscellaneous building and a much expanded parking area. Potential exposures toconstruction workers during excavation and building activities are possible. However paving andbuilding structures cover all existing soils and have eliminate any potential exposures, direct orindirect via soil for future site workers.

Remedial Goal Options (RGOs) are outlined in this document to assess potential cleanup it levelsif site cleanup is necessary. RGOs were generated for surface soil for the base worker andresidential scenarios, surface and subsurface soil for the construction worker scenario, and forpotable use of groundwater.

In the calculation of RGOs, concentrations for each individual chemical corresponding to ELCRsof 1E-04, 1E-05, and 1E-06 (for carcinogenic effects) and HQs of 3, 1, and 0.1 (fornoncarcinogenic: effects) are calculated for each chemical that has an ELCR exceeding 1E-06 or aHQ exceeding 0.1. RGOs are specific to a certain risk scenario. RGOs were calculated, as perFlorida DEP and USEPA Region IV guidance, by rearranging the site specific risk equations andsolving for the concentration term for the target risk. RGOs were generated for those chemicalsthat were significant contributors to hazard, i.e. chemicals with an individual risk contribution ofgreater than 1E-06 or HQ of greater than 0.1. The corresponding state and federal guidance andresults of the RGO calculations are presented in Table 2-44.

2.7.6 Ecological Risk Assessment

Conditions at OU-7 provide little usable or preferred habitat for terrestrial species. Littlevegetation is available for food or cover, and the shallow depth of soil to bedrock is expected torestrict the activities of burrowing animals. Base personnel activity at OU-7 likely inhibit theactivities of animals. Although avian species may potentially visit the site, it is highly unlikely thatthey would derive a significant portion of their diet from the limited resources available at OU-7.Therefore, while constituent concentrations detected at OU-7 might potentially representecotoxicological hazard, it is unlikely that terrestrial biota would inhabit or frequent the site.

While there is limited vegetative cover at the site, groundwater may be a potential source ofexposure to plants via their root systems. Possible uptake would be modified by a variety offactors such as alkalinity of soils, organic content of soils, possible synergistic or antagonisticeffects of multiple compounds, and the individual chemical and physical characteristics of

TABLE 2-44RISK-BASED REMEDIAL GOAL OPTIONS

HYPOTHETICAL FUTURE ADULT RESIDENT ATOU-7, ENTOMOLOGY STORAGE AREA

GROUNDWATER (mg/L)

COMPOUNDS

SITE SPECIFIC REMEDIALGOAL OPTIONSHAZARD INDEX

SITE SPECIFIC REMEDIALGOAL OPTIONS

CARCINOGENIC RISKEPA

MAXIMUMCONTAINMENT

LEVEL

FloridaDrinking

WaterStandard0.1 1.0 3.0 1E-06 1E-05 1E-04

VOCsBromodichloromethane NAP NAP NAP 1.4E-03 1.4E-02 1.4E-01 1E-01 NSc

Dibromochloromethane NAP NAP NAP 1.0E-03 1.0E-02 1.0E-01 1E-01 NSc

PesticidesAlpha-BHC NAP NAP NAP 1.4E-05 1.4E-04 1.4E-03 NA NSc

DDD 1.8-03 1.8E-02 5.5E-02 3.5E-04 3.5E-03 3.5E-02 NA NSc

MetalsAluminum 3.7E+00 3.7E+02 1.1E+02 NAP NAP NAP 5E-02 to 2E-01a 0.2b

Arsenic 1.1E-03 3.3E-02 3.3E-02 5.7E-05 5.7E-04 5.7E-03 5E-02 5E-02Cadmium 1.8E-03 5.5E-02 5.5E-02 NAP NAP NAP 5E-03 5E-03Chromium (VI) 1.8E-01 5.5E-01 5.5E-01 NAP NAP NAP 1E-01 1E-01Manganese 1.8E-02 5.5E-01 5.5E-01 NAP NAP NAP 0.05a 0.05b

NAP = Not Applicable NS = No Standard ELCR = Excess Lifetime Cancer Risk HI = Hazard Index a USEPA Secondary Drinking Water Standard b Florida Secondary Drinking Water Standard c There are no Drinking Water Standards for these compounds. However, Florida Groundwater Guidance Concentrations are available as follows: bromodichloromethane - 0.6 ug/L; dibromochloromethane - 1 ug/L; alpha-BHC - 0.05 ug/L; and DDD - 0. 1 ug/L.

TABLE 2-44RISK-BASED REMEDIAL GOAL OPTIONS

AND FDEP SOIL TARGET LEVELSHYPOTHETICAL CURRENT BASE WORKER (MOWING SCENARIO) AT

OU-7, ENTOMOLOGY STORAGE AREASOIL (mg/kg)

COMPOUNDS

SITE SPECIFIC REMEDIALGOAL OPTIONSHAZARD INDEX

SITE SPECIFIC REMEDIALGOAL OPTIONS

CARCINOGENIC RISKFDEP

Soil Target LevelsBased on an of 1E-

06 / HI of 10.1 1.0 3.0 1E-06 1E-05 1E-04

MetalsArsenic NAP NAP NAP 1.7E+01 1.7E+02 1.7E+03 3E+00

NAP = Not ApplicableELCR = Excess Lifetime Cancer RiskHI = Hazard Index

TABLE 2-44RISK-BASED REMEDIAL GOAL OPTIONS

AND FDEP SOIL TARGET LEVELSHYPOTHETICAL FUTURE ADULT RESIDENT AT

OU-7, ENTOMOLOGY STORAGE AREASOIL (mg/kg)

COMPOUNDS

SITE SPECIFIC REMEDIALGOAL OPTIONSHAZARD INDEX

SITE SPECIFIC REMEDIALGOAL OPTIONS

CARCINOGENIC RISKFDEP

Soil Target LevelsBased on an ELCR

of 1E-06 / HI of 10.1 1.0 3.0 1E-06 1E-05 1E-04

BNAsBenzo(b)pyrene NAP NAP NAP 2.2E+01 2.2E+00 2.2E+01 1E-01Dibenzo(a,h)anthracene NAP NAP NAP 2.2E-01 2.2E+00 2.2E+01 1E-01

Pesticides/PCBsChlordane Isomers NAP NAP NAP 1.0E+00 1.0E+00 1.0E+02 5E-01

MetalsArsenic NAP NAP NAP 1.4E+00 1.4E+01 1.4E+02 7E-01Thallium 5.0E+00 5.0+01 1.5E+02 NAP NAP NAP NA

NAP = Not ApplicableELCR = Excess Lifetime Cancer RiskHI = Hazard Index

TABLE 2-44RISK-BASED REMEDIAL GOAL OPTIONS

AND FDEP SOIL TARGET LEVELSHYPOTHETICAL FUTURE CHILD RESIDENT AT

OU-7, ENTOMOLOGY STORAGE AREASOIL (mg/kg)

COMPOUNDS

SITE SPECIFIC REMEDIALGOAL OPTIONSHAZARD INDEX

SITE SPECIFIC REMEDIALGOAL OPTIONS

CARCINOGENIC RISKFDEP

Soil Target LevelsBased on an ELCR

of 1E-06 / HI of 10.1 1.0 3.0 1E-06 1E-05 1E-04

BNAsBenzo(a)anthracene NAP NAP NAP 1.1E+00 1.1E+01 1.1E+02 1.4E+00Benzo(b)pyrene NAP NAP NAP 1.1E-01 1.1E+00 1.1E+01 1.0E-01Benzo(a,h)anthracene NAP NAP NAP 1.1E+00 1.1E+01 1.1E-02 1.4E+00Dibenzo(a,h)anthracene NAP NAP NAP 1.1E-01 1.1E+00 1.1E+01 1.0E-01

Pesticides/PCBsChlordane Isomers 3.4E-01 3.4E+00 1.0E+01 5.1E-01 5.1E+00 5.1E+01 5.0E-01

MetalsAluminum 7.2E+03 7.2E+04 2.2E+05 NAP NAP NAP 7.5E+04Arsenic 2.3E+00 2.3E+01 6.9E+01 6.0E-01 6.0E-01 6.0E+00 7.0E-01

NAP = Not ApplicableELCR = Excess Lifetime Cancer RiskHI = Hazard Index

TABLE 2-44RISK-BASED REMEDIAL GOAL OPTIONS

AND FDEP SOIL TARGET LEVELSHYPOTHETICAL FUTURE CONSTRUCTION WORKER AT

OU-7, ENTOMOLOGY STORAGE AREASUBSURFACE SOIL (mg/kg)

COMPOUNDS

SITE SPECIFIC REMEDIALGOAL OPTIONSHAZARD INDEX

SITE SPECIFIC REMEDIALGOAL OPTIONS

CARCINOGENIC RISKFDEP

Soil Target LevelsBased on an ELCR

of 1E-06 / HI of 10.1 1.0 3.0 1E-06 1E-05 1E-04

BNAsBenzo(b)pyrene NAP NAP NAP 2.2E+01 2.2E+00 2.2E+01 1E-01Dibenzo(a,h)anthracene NAP NAP NAP 2.2E-01 2.2E+00 2.2E+01 1E-01

Pesticides/PCBsChlordane Isomers NAP NAP NAP 1.0E+00 1.0E-01 1.0E+02 5E-01

MetalsArsenic NAP NAP NAP 1.4E+00 1.4E+01 1.4E+02 7E-01Thallium 5.0E+00 5.05E+01 1.5E+02 NAP NAP NAP NA

NAP = Not ApplicableELCR = Excess Lifetime Cancer RiskHI = Hazard Index

TABLE 2-44RISK-BASED REMEDIAL GOAL OPTIONS

AND FDEP SOIL TARGET LEVELSHYPOTHETICAL FUTURE CONSTRUCTION WORKER AT

OU-7, ENTOMOLOGY STORAGE AREASUBSURFACE SOIL (mg/kg)

COMPOUNDS

SITE SPECIFIC REMEDIALGOAL OPTIONSHAZARD INDEX

SITE SPECIFIC REMEDIALGOAL OPTIONS

CARCINOGENIC RISKFDEP

Soil Target LevelsBased on an ELCR

of 1E-06 / HI of 10.1 1.0 3.0 1E-06 1E-05 1E-04

MetalsAntimony 8.5E+00 8.5E+01 2.6E+02 NAP NAP NAP 2.2E+02Arsenic 6.4E+00 6.4E+01 1.9E+02 9.9E+00 9.9E+01 9.9E+02 3.1E+00

NAP = Not ApplicableELCR = Excess Lifetime Cancer RiskHI = Hazard Index

64

the COCs in groundwater. Comparison with literature toxicity information indicates that theconcentrations at OU-7 should not be significant.

In summary, there is no evidence of significant use of the site as habitat by ecological receptors.Urbanization and base operations have already replaced this ecosystem and rendered its current useand likely future use as poor quality habitat. However, the potential for the migration of thesecompounds into boundary canal and other downgradient water bodies may need to be exploredfurther.

Uncertainties in Ecological Risk. Although the effects of constituents on ecological receptors area concern, it is difficult to predict if observed effects on individual populations will result in any realdamage to the ecosystem. Populations are dynamic; therefore, information concerning the normalrange of variability within the population needs to be known. Sublethal effects, which may be veryimportant to overall ecosystem health, are difficult to detect, and constituents present at lowconcentrations may not kill organisms directly but may greatly diminish their ability to survive andreproduce. Finally, it is important to note that constituent contamination is not the only manner inwhich humans impact ecosystems. Habitat destruction from development, agriculture, recreation, etc.,is likely the major way humans cause ecological impacts (Moriarty, 1988).

2.8 DESCRIPTION OF ALTERNATIVES

The USAF only considered two alternatives in the Feasibility Study (FS) to address the contaminationidentified at OU-7: Alternative 1 - No Action, and Alternative 2 - Access and Use Restrictions forSoils and Groundwater and Groundwater Monitoring. These two alternatives were screened basedon the criteria of effectiveness, implementability, and cost. These two alternatives were then carriedforward through complete evaluation. These two alternatives were evaluated against the nineCERCLA criteria requirements for selecting a remedial alternative. These nine criteria includeeffectiveness, implementability, cost, state acceptance, community acceptance, long-termeffectiveness and permanence, reduction of mobility, toxicity, or volume through treatment,compliance with ARARs, short-term effectiveness, and overall protection of human health and theenvironment. A summary of the two alternatives described in the Feasibility Study is presented belowwhile each is discussed in greater detail in the FS.

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2.8.1 Alternative 1 - No Action

The No-Action Alternative is evaluated as required by the National Oil and Hazardous SubstancesPollution Contingency Plan (NCP), the regulation implementing CERCLA, for comparison with otheralternatives. The No-Action Alternative takes into account the capping of the site through newconstruction and includes one 5-year site review involving literature searches, site walks, interviews,and minimal sampling.

Under current land use conditions, this alternative poses an acceptable excess cancer and noncancerrisk, per USEPA guidelines. The only completed exposure pathway is that of a base worker droppingoff and picking up supplies. The total excess cancer risk to the base worker was estimated at 2E-06,which is considered an acceptable risk by USEPA. The total estimated noncancer risk of 0.02 is alsoconsidered acceptable by USEPA.

The present worth analysis is used to evaluate expenditures that occur over different time periods bydiscounting all future cost to a common base year, usually the current year. This allows the cost ofremedial action alternatives to be compared on the basis on a single figure representing the amountof money that, if invested in the base year and disbursed as needed, would be sufficient to cover allcost associated with the remedial action over its planned life. The present-worth cost of thisalternative is estimated at $24,270. This cost consist of one 5year site review with an estimated costof $29,500. The cost of the 5-year site review has been discounted to present value using a 5%discount rate.

2.8.2 Alternative 2 - Access And Use Restrictions For Soil And Groundwater And Groundwater Monitoring

This alternative takes into account the capping of the site through the construction of buildings,pavement, and grassways as an effective barrier to prevent exposure to soil and groundwatercontaminants, access and use restrictions, and monitoring well installation and sampling.

Rebuilding over OU-7 as part of the Base Supply, Civil Engineering, and POL Operations Area,effectively provides a natural barrier or cap from exposure to the underlying soil and groundwater.Institutional controls would be enacted to prevent residential development and placement of a potablewell.

Access and use restrictions would be developed and enforced by the current landowner, the U.S. AirForce.

66

This alternative includes land use and access restrictions in the form of digging/excavation restrictionsaround the areas where elevated concentrations of arsenic were detected in the soil and groundwater(north and south excavation areas). Under the current land use, access to the area is limited given thesite is located within the cantonment area, which is fenced and patrolled by Base security. Future landuse of the site is inherently limited by its proximity to the airfield and ordnance storage areas. Ifownership of the base is transferred to private or non-DOD entities, use restrictions could beestablished that would prevent schools, playgrounds, hospitals, and housing from being built, andprevent placement of a potable well at OU-7 until contaminants in the soils and/or groundwater arebelow levels of concern. If the base is deactivated and a transfer of ownership occurs, the newlandowner would be responsible for enforcing these restrictions.

This alternative also includes the installation of one new monitoring well as depicted in Figure 2-11.The new well and two existing wells (MW-1-204-1 OLD and MW-1-207-1) will be sampled quarterlyfor one year, semi-annually for one year, and annually for the next three years if necessary. Sampleswill be analyzed for organochlorine pesticides, BNAs and TAL metals.

One 5-year site review is included which involves literature searches, site walks, interviews, minimalsampling, and a groundwater sampling review to determine the effectiveness of the remedy. Thisalternative is protective of human health and the environment under the current and potential futureland use conditions and relies on institutional controls to prevent exposure for the hypothetical futureresidential land use scenario. This alternative does not actively reduce the toxicity, mobility or volumeof the potential contaminants in the soil, and relies on control measures to prevent access or exposureto contaminated areas at OU-7.

The present-worth cost of this alternative is estimated at $163,467. This cost consists of an estimatedinitial capital cost of $21,920, one year of quarterly groundwater sampling, one year of semi-annualgroundwater sampling, three years of annual groundwater sampling if necessary with an estimatedcost of $124,200, and one 5-year site review with an estimated cost of $29,500. The cost of theannual O&M reviews and the 5-year site review have been discounted to present value using a 5%discount rate.

67

2.9 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES

An evaluation and comparison of the alternatives is presented in Table 2-45. The comparison is basedon the nine key criteria required under the National Contingency Plan and CERCLA Section 121 foruse in evaluation of remedial alternatives by USEPA. The nine criteria are as follows:

! Overall protection of human health and the environment;! Compliance with Applicable or Relevant and Appropriate Requirements;! Long-term effectiveness and permanence;! Reduction of toxicity, mobility, or volume;! Short-term effectiveness;! Cost;! State acceptance; and! Community acceptance.

2.9.1 Overall Protection of Human Health and the Environment

The estimated excess cancer and noncancer risks to humans under current and future industriallanduse conditions are within acceptable guidelines set by USEPA. The excess cancer risk for theworst-case scenario, a future construction worker exposed to surface soils, is estimated at 3x10-6. Thenoncancer risk is estimated at 0.5. The excess cancer risk range considered acceptable by USEPA is10-4 to 10-6. The noncancer limit considered acceptable by USEPA is 1. Predicted blood lead level fora hypothetical future child resident was estimated at 3.4 µg/dL, which is below the USEPA guidelineof 10 µg/dL, and indicates a low level of concern for lead exposure if the site were re-developed forfuture land use.

Both of the alternatives are protective of human health under current and potential industrial land useconditions based on the site-specific risk assessment performed for OU-7. However, the no-actionalternative may not be protective of the environment. Arsenic levels in the groundwater exceed thefederal and state MCLs very locally in the south excavation. Alternative 2 is protective of theenvironment because it addresses the concentrations of arsenic in the groundwater by providinggroundwater monitoring to assess the migration of contaminants over time.

TABLE 2-45

COMPARATIVE ANALYSIS OF REMEDIAL ALTERNATIVES, OU-7

Remedial Alternative

Evaluation CriteriaAlternative 1

No ActionAlternative 2

Capping/Institutional Controls/GW Monitoring

Overall Protection of HumanHealth & Environment

? O

Compliance w/ARARs ? ? *

Long-Term Effectivenessand Permanence

? ? *

Reduction of Toxicity,Mobility, or Volume

? (1) ? (1)

Short-Term Effectiveness O O

Implementability Easy Easy

Estimated Present Worth $24,270 $163,467

? Does not meet criterionO Meets criterion* Has potential to meet criterion(1) 1994 IRA removed over 4,300 tons of contaminated soils which, if included as a part of

this comparative analysis. would satisfy this criterion.

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2.9.2 Compliance with ARARs

None of the alternatives meet the groundwater ARARs. Arsenic detected in groundwater is abovethe federal and state promulgated standards and there are no ARARs for soils. Neither of thealternatives meet the TBC guidelines for soil cleanup levels. However, a waiver to the chemicalspecific ARARs is appropriate because Alternative 2 will attain the standard of performanceconsidered protective of human health and the environment through access and use restrictions andassesses the compliance of groundwater ARARs through annual groundwater monitoring and a5-year site review. Alternative 2 also prevents exposure to soils through access and use restrictions.

2.9.3 Long-Term Effectiveness and Permanence

Alternatives 1 does not provide permanent solutions to the remedial action objectives. Alternative 2permanently reduces the risks from both inhalation and ingestion of soils and groundwater by cappingthe site and by the use of access and use restrictions at OU-7.

2.9.4 Reduction of Mobility, Toxicity, or Volume Through Treatment

Neither Alternative 1 or 2 involve treatment. However, as discussed above, the 1994 IRA wasimplemented to reduce the mobility, toxicity, and volume of the contaminated soils and removed themajority of the contaminants of concern which was the source of the groundwater contamination.

2.9.5 Short-Term Effectiveness

Neither Alternatives 1 or 2 are expected to pose significant risk to the community or workers duringimplementation. There are no anticipated adverse environmental impacts from either of thealternatives.

2.9.6 Implementability

Alternatives 1 and 2 are easily implementable.

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2.9.7 Cost

Alternative 1 provides protection to human health, but may not adequately protect the environmentand has a 5-year present worth of $24,270. Alternative 2 uses capping and institutional controls tolimit access to the contaminated soils and groundwater monitoring to assess compliance with ARARsand to detect any future migration of contaminants over time. Alternative 2 would cost approximately$163,467.

2.9.8 State and Community Acceptance

State and community concerns will be addressed in the proposed plan.

2.10 SELECTED REMEDY

Based upon consideration of the requirements of CERCLA, the detailed evaluation of the alternativesand public comments, the U.S. Air Force, in concurrence with the USEPA and the state of Florida,has determined that Alternative 2 - Access and Use Restrictions for Soil and Groundwater andGroundwater Monitoring is the most appropriate course of action at OU-7.

This alternative is protective of human health and the environment under current and future industriallanduse conditions. The groundwater will be monitored quarterly for one year, semi-annually for oneyear, and annually for three years if necessary to assess any future migration of contaminants overtime. After the 5-year monitoring period, EPA, FDEP, and the USAF will evaluate the effectivenessof the remedy and the need for continued groundwater access restrictions. The selected remedy hasbeen accepted by the state and community concerns have been addressed in the ResponsivenessSummary of this ROD.

A 5-year review will be conducted to determine whether the remedy remains protective of humanhealth and the environment and to evaluate the need for continued groundwater access restrictions.

2.11 STATUTORY DETERMINATIONS

Under its legal authorities, EPA’s primary responsibility at Superfund sites is to undertake remedialactions that achieve adequate protection of human health and the environment. The selected remedyreduces and controls the existing risk to human health by relying on capping

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and institutional controls to prevent exposure to soils and groundwater. The selected remedy isprotective of the environment by providing capping and groundwater monitoring to detect and/orprevent surface and subsurface exposure to arsenic contaminated soils and groundwater. In addition,Section 121 of CERCLA establishes several other statutory requirements and preferences. Thesespecify that when complete, the selected remedial action for this site must comply with applicable orrelevant and appropriate environmental standards established under Federal and State environmentallaws unless a statutory waiver is justified. The selected remedy does not meet ARARs as arsenic hasbeen detected in groundwater at concentrations greater than Federal and State MCLs. No ARARsexist for soil, but the selected remedy does not meet TBC guidelines for soil cleanup levels. However,a waiver to the chemical specific ARARs is appropriate because Alternative 2 will attain the standardof performance considered protective of human health and the environment through access and userestrictions and assesses the compliance of groundwater ARARs through annual groundwatermonitoring and a 5-year site review. Alternative 2 also prevents exposure to soils through access anduse restrictions. The selected remedy also must be cost-effective and utilize permanent solutions andalternative treatment technologies or resource recovery technologies to the maximum extentpracticable. The selected remedy has been determined to be cost-effective and utilizes permanentsolutions.

Finally, the statute includes a preference for remedies that permanently and significantly reduce thevolume, toxicity, or mobility of hazardous wastes as their principal element. The selected remedy doesnot involve treatment. However, as previously discussed, the 1994 IRA was implemented to reducethe mobility, toxicity, and volume of the contaminated soils and removed the majority of thecontaminants of concern which was the source of the groundwater contamination. The selection ofAlternative 2-Access and Use Restrictions for Soil and Groundwater and Groundwater Monitoringsatisfies the statutory determinations for this site.

2.12 DOCUMENTATION OF SIGNIFICANT CHANGES

The Proposed Plan for OU-7 was released for public comment in November 1997. The Proposed Planidentified Alternative 2 - Access and Use Restrictions for Soil and Groundwater and GroundwaterMonitoring as the preferred alternative. EPA reviewed all written and verbal comments submittedduring the public comment period. Upon review of these comments, it was determined that nosignificant changes to the remedy, as it was originally identified in the Proposed Plan, were necessary.

Homestead Air Force Base, FloridaOperable Unit No. 7,Entomology Storage Area

Responsiveness Summary for theRecord of Decision

RESPONSIVENESS SUMMARY

FOR THE

RECORD OF DECISION

The responsiveness summary serves three purposes. First, it provides regulators with informationabout the community preferences regarding both the remedial alternatives and general concerns aboutOperable Unit No. 7, Homestead ARB. Second, the responsiveness summary documents how publiccomments have been considered and integrated into the decision making process. Third, it providesUSEPA with the opportunity to respond to each comment submitted by the public on the record.

The Remedial Investigation/Baseline Risk Assessment Report, Feasibility Study and Proposed Planfor Homestead ARB, OU-7 were released to the public in April 1996, November 20, 1997, andNovember 20, 1997, respectively. These documents were made available to the public in both theadministrative record and an information repository maintained at the Air Force Base ConversionAgency OL-Y office.

A public comment period was held from November 20, 1997 to December 22, 1997 as part of thecommunity relations plan for OU-7. A public meeting was held on November 20, 1997, at 7:00 p.m.at South Dade Senior High School. Public Notices were published in the Miami Herald on November16, 1997, and in the South Dade News Leader and The Courier on November 17, 1997. At thismeeting, the USAF and Dade County Environmental Resource Management (DERM), were preparedto discuss the Remedial Investigation, the Baseline Risk Assessment, the Feasibility Study, and thePreferred Alternative for this OU as described in the Proposed Plan.

There were no comments at the public meeting regarding the selected alternative for OU-7/Site SS-7.Additionally, no comments were received during the public comment period.